build: enable license header linting for benchmark tests

Enables license header linting for the benchmark tests
folder. This seems needed because in order to sync these files
into g3, the license header must be correct/added.

Related to #19596.

Author: devversion

tslint.json

@@ -169,7 +169,8 @@
     }, "src/!(e2e-app|components-examples|universal-app|dev-app)/**/!(*.spec).ts"],
     "require-license-banner": [
       true,
-      "src/!(e2e-app|components-examples|universal-app)/**/!(*.spec).ts"
+      "src/!(e2e-app|components-examples|universal-app)/**/!(*.spec).ts",
+      "test/benchmarks/**/*.ts"
     ],
     "no-cross-entry-point-relative-imports": [
       true,