build: remove unreferenced tsconfig-build.json files (#30858)

These are no longer needed since Bazel generates a tsconfig for each compilation

PR Close #30858

packages/compiler/testing/tsconfig-build.json

@@ -1,24 +0,0 @@
-{
-  "extends": "../tsconfig-build.json",
-
-  "compilerOptions": {
-    "baseUrl": ".",
-    "rootDir": "../",
-    "paths": {
-      "@angular/compiler": ["../../../dist/packages/compiler"],
-      "@angular/core": ["../../../dist/packages/core"]
-    },
-    "outDir": "../../../dist/packages/compiler"
-  },
-
-  "files": [
-    "testing.ts",
-    "../../../node_modules/zone.js/dist/zone.js.d.ts"
-  ],
-
-  "angularCompilerOptions": {
-    "annotateForClosureCompiler": true,
-    "skipMetadataEmit": true,
-    "skipTemplateCodegen": true
-  }
-}