test(@angular/build): add an E2E test for absolute include paths for unit tests

An additional E2E test has been added that tests the usage of an absolute
path for the `unit-test` command line `--include` option.

Author: clydin

tests/legacy-cli/e2e/tests/vitest/absolute-include.ts

@@ -0,0 +1,12 @@
+import assert from 'node:assert/strict';
+import { applyVitestBuilder } from '../../utils/vitest';
+import { ng } from '../../utils/process';
+import path from 'node:path';
+
+export default async function (): Promise<void> {
+  await applyVitestBuilder();
+
+  const { stdout } = await ng('test', '--include', path.resolve('src/app/app.spec.ts'));
+
+  assert.match(stdout, /1 passed/, 'Expected 1 test to pass.');
+}