fix(@angular/build): ensure disabled vitest config loading

With the experimental `unit-test` builder with the `vitest` runner, the underlying
vitest execution will no longer attempt to load external configuration files.
The current internal vitest usage does not support integration of external
configuration files.

(cherry picked from commit 25c80b3)

Author: clydin

packages/angular/build/src/builders/unit-test/builder.ts

@@ -217,39 +217,47 @@ export async function* execute(
 
       await writeTestFiles(result.files, outputPath);
 
-      instance ??= await startVitest('test', undefined /* cliFilters */, undefined /* options */, {
-        test: {
-          root: outputPath,
-          globals: true,
-          setupFiles,
-          // Use `jsdom` if no browsers are explicitly configured.
-          // `node` is effectively no "environment" and the default.
-          environment: browser ? 'node' : 'jsdom',
-          watch: normalizedOptions.watch,
-          browser,
-          reporters: normalizedOptions.reporters ?? ['default'],
-          coverage: {
-            enabled: normalizedOptions.codeCoverage,
-            excludeAfterRemap: true,
-          },
-          ...debugOptions,
+      instance ??= await startVitest(
+        'test',
+        undefined /* cliFilters */,
+        {
+          // Disable configuration file resolution/loading
+          config: false,
         },
-        plugins: [
-          {
-            name: 'angular-coverage-exclude',
-            configureVitest(context) {
-              // Adjust coverage excludes to not include the otherwise automatically inserted included unit tests.
-              // Vite does this as a convenience but is problematic for the bundling strategy employed by the
-              // builder's test setup. To workaround this, the excludes are adjusted here to only automatically
-              // exclude the TypeScript source test files.
-              context.project.config.coverage.exclude = [
-                ...(normalizedOptions.codeCoverageExclude ?? []),
-                '**/*.{test,spec}.?(c|m)ts',
-              ];
+        {
+          test: {
+            root: outputPath,
+            globals: true,
+            setupFiles,
+            // Use `jsdom` if no browsers are explicitly configured.
+            // `node` is effectively no "environment" and the default.
+            environment: browser ? 'node' : 'jsdom',
+            watch: normalizedOptions.watch,
+            browser,
+            reporters: normalizedOptions.reporters ?? ['default'],
+            coverage: {
+              enabled: normalizedOptions.codeCoverage,
+              excludeAfterRemap: true,
             },
+            ...debugOptions,
           },
-        ],
-      });
+          plugins: [
+            {
+              name: 'angular-coverage-exclude',
+              configureVitest(context) {
+                // Adjust coverage excludes to not include the otherwise automatically inserted included unit tests.
+                // Vite does this as a convenience but is problematic for the bundling strategy employed by the
+                // builder's test setup. To workaround this, the excludes are adjusted here to only automatically
+                // exclude the TypeScript source test files.
+                context.project.config.coverage.exclude = [
+                  ...(normalizedOptions.codeCoverageExclude ?? []),
+                  '**/*.{test,spec}.?(c|m)ts',
+                ];
+              },
+            },
+          ],
+        },
+      );
 
       // Check if all the tests pass to calculate the result
       const testModules = instance.state.getTestModules();