fix(@angular/build): adjust sourcemap sources when Vitest wrapper is bypassed

When code coverage is disabled, the Vitest builder bypasses the secondary import wrapper
and serves the compiled output directly as the test file. This caused sourcemaps to be
incorrect because the `sources` field in the map (relative to the build root) was being
resolved relative to the test file's location.

This commit adjusts the `sources` in the sourcemap to be relative to the test file's
directory, ensuring correct source mapping in debuggers.

Author: clydin

packages/angular/build/src/builders/unit-test/runners/vitest/plugins.ts

@@ -291,6 +291,17 @@ export function createVitestPlugins(pluginOptions: PluginOptions): VitestPlugins
           if (map) {
             if (!map.sources?.length && !map.sourcesContent?.length && !map.mappings) {
               map.sources = ['virtual:builder'];
+            } else if (!vitestConfig.coverage.enabled && Array.isArray(map.sources)) {
+              map.sources = (map.sources as string[]).map((source) => {
+                if (source.startsWith('angular:')) {
+                  return source;
+                }
+
+                // source is relative to the workspace root because the output file is at the root of the output.
+                const absoluteSource = path.join(workspaceRoot, source);
+
+                return toPosixPath(path.relative(path.dirname(id), absoluteSource));
+              });
             }
           }