refactor(compiler-cli): remove hardcoded config for unused standalone imports rule enablement (angular#61622)

The hardcoded config was introduced because suppressing the diagnostic
via `extendedDiagnostics` in the TS config was unreliable in google3.
This has since been fixed and the workaround is no longer needed.

PR Close angular#61622

Author: Jonathan Meier

packages/compiler-cli/src/ngtsc/validation/src/config.ts

@@ -15,7 +15,6 @@ import {SourceFileValidatorRule} from './rules/api';
 import {InitializerApiUsageRule} from './rules/initializer_api_usage_rule';
 import {UnusedStandaloneImportsRule} from './rules/unused_standalone_imports_rule';
 import {TemplateTypeChecker, TypeCheckingConfig} from '../../typecheck/api';
-import {UNUSED_STANDALONE_IMPORTS_RULE_ENABLED} from './config';
 
 /**
  * Validates that TypeScript files match a specific set of rules set by the Angular compiler.
@@ -31,15 +30,13 @@ export class SourceFileValidator {
   ) {
     this.rules = [new InitializerApiUsageRule(reflector, importedSymbolsTracker)];
 
-    if (UNUSED_STANDALONE_IMPORTS_RULE_ENABLED) {
-      this.rules.push(
-        new UnusedStandaloneImportsRule(
-          templateTypeChecker,
-          typeCheckingConfig,
-          importedSymbolsTracker,
-        ),
-      );
-    }
+    this.rules.push(
+      new UnusedStandaloneImportsRule(
+        templateTypeChecker,
+        typeCheckingConfig,
+        importedSymbolsTracker,
+      ),
+    );
   }
 
   /**