fix(@schematics/angular): defer karma config deletion in Karma to Vitest migration

This commit resolves a race condition in the Karma-to-Vitest migration where shared configuration files were deleted prematurely within the schematic transaction. Previously, the routine erased the target file upon discovering it was identical to boilerplate, which blinded other referring projects to extraction metadata.

The solution introduces analysis object caching so AST parsing occurs exactly once per discrete path. Deletion operations are deferred and batch-executed at the end of workspace processing. This mechanism guarantees continuous readability across iterating dependencies and yields operational speed improvements via memoized checks.