refactor: inline truncatedId and simplify trim regex

- Inline truncatedId() into AliasMap.set(): single-use private function
  with simple logic, inlining removes unnecessary indirection
- Simplify part.replace(/^_/, '').replace(/_$/, '') to part.replace(/^_|_$/g, '')

Author: recca0120

packages/phpunit/src/TestIdentifier/PestV2Fixer.ts

@@ -36,9 +36,7 @@ function decodeEvaluable(encoded: string): string {
     const describeParts = segments.slice(0, -1);
 
     const decoded = [
-        ...describeParts.map((part) =>
-            decodeDescribePart(part.replace(/^_/, '').replace(/_$/, '')),
-        ),
+        ...describeParts.map((part) => decodeDescribePart(part.replace(/^_|_$/g, ''))),
         decodeWords(testPart).join(' '),
     ].join(' \u2192 ');
 

packages/phpunit/src/TestIdentifier/PestV3Fixer.ts

@@ -1,21 +1,12 @@
 // Pest v3 bug: Str::beforeLast uses mb_strrpos (char offset) with substr (byte offset).
 // The → character (U+2192) is 3 UTF-8 bytes but 1 char, so names are truncated
 // by 2 bytes per → character.
-function truncatedId(id: string): string | undefined {
-    const count = (id.match(/\u2192/g) ?? []).length;
-    if (count === 0) {
-        return undefined;
-    }
-
-    return id.slice(0, -count * 2);
-}
-
 export class AliasMap<T> extends Map<string, T> {
     override set(id: string, item: T): this {
         super.set(id, item);
-        const truncated = truncatedId(id);
-        if (truncated) {
-            super.set(truncated, item);
+        const count = id.match(/\u2192/g)?.length ?? 0;
+        if (count > 0) {
+            super.set(id.slice(0, -count * 2), item);
         }
 
         return this;