Models with custom materialization cannot be deleted

[MikeWallis42]

SQLMesh version: 0.227.1
sqlglot version: 27.28.1

When running sqlmesh janitor or sqlmesh destroy any model that has a custom materialization fails to be deleted because the custom materialization isn't loaded.

Traceback (most recent call last):
  File ".venv/lib/python3.12/site-packages/sqlmesh/utils/concurrency.py", line 69, in _process_node
    self.fn(node)
  File ".venv/lib/python3.12/site-packages/sqlmesh/utils/concurrency.py", line 172, in <lambda>
    lambda s_id: fn(snapshots_by_id[s_id]),
                 ^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/snapshot/evaluator.py", line 537, in <lambda>
    lambda s: self._cleanup_snapshot(
              ^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/snapshot/evaluator.py", line 1337, in _cleanup_snapshot
    evaluation_strategy = _evaluation_strategy(snapshot, adapter)
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/snapshot/evaluator.py", line 1683, in _evaluation_strategy
    _, klass = get_custom_materialization_type_or_raise(snapshot.custom_materialization)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/snapshot/evaluator.py", line 2918, in get_custom_materialization_type_or_raise
    types = get_custom_materialization_type(name, raise_errors=True)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/snapshot/evaluator.py", line 2900, in get_custom_materialization_type
    raise e
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/snapshot/evaluator.py", line 2897, in get_custom_materialization_type
    raise ConfigError(f"Materialization strategy with name '{name}' was not found.")
sqlmesh.utils.errors.ConfigError: Materialization strategy with name 'delsert' was not found.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File ".venv/bin/sqlmesh", line 10, in <module>
    sys.exit(cli())
             ^^^^^
  File ".venv/lib/python3.12/site-packages/click/core.py", line 1161, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/click/core.py", line 1082, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/click/core.py", line 1697, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/click/core.py", line 1443, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/click/core.py", line 788, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/click/decorators.py", line 33, in new_func
    return f(get_current_context(), *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/cli/__init__.py", line 29, in wrapper
    return handler(sqlmesh_context, lambda: func(*args, **kwargs))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/cli/__init__.py", line 51, in _debug_exception_handler
    return func()
           ^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/cli/__init__.py", line 29, in <lambda>
    return handler(sqlmesh_context, lambda: func(*args, **kwargs))
                                            ^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/analytics/__init__.py", line 82, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/cli/main.py", line 643, in janitor
    ctx.obj.run_janitor(ignore_ttl, **kwargs)
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/analytics/__init__.py", line 110, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/context.py", line 872, in run_janitor
    self._run_janitor(ignore_ttl)
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/context.py", line 2868, in _run_janitor
    delete_expired_snapshots(
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/janitor.py", line 168, in delete_expired_snapshots
    snapshot_evaluator.cleanup(
  File ".venv/lib/python3.12/site-packages/sqlmesh/core/snapshot/evaluator.py", line 535, in cleanup
    concurrent_apply_to_snapshots(
  File ".venv/lib/python3.12/site-packages/sqlmesh/utils/concurrency.py", line 170, in concurrent_apply_to_snapshots
    return concurrent_apply_to_dag(
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/utils/concurrency.py", line 212, in concurrent_apply_to_dag
    ).run()
      ^^^^^
  File ".venv/lib/python3.12/site-packages/sqlmesh/utils/concurrency.py", line 64, in run
    self._finished_future.result()
  File ".local/share/uv/python/cpython-3.12.11-macos-aarch64-none/lib/python3.12/concurrent/futures/_base.py", line 456, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File "local/share/uv/python/cpython-3.12.11-macos-aarch64-none/lib/python3.12/concurrent/futures/_base.py", line 401, in __get_result
    raise self._exception
sqlmesh.utils.concurrency.NodeExecutionFailedError: Execution failed for node SnapshotId<"iceberg"."explorer_ipcv"."pre_care_record_range_v1": 2524880239>