test(git): assert relative URLs in gitApiHttp stage/unstage tests (#1615)

The runtime URL refactor in #1228 switched gitApiHttp's buildUrl from
absolute window-origin URLs to the relative URLs returned by the default
runtime URL resolver, but gitApiHttp.test.ts kept asserting the old
absolute URLs. The two index-mutation tests have failed ever since
(no CI step runs the test suite, so it went unnoticed). Update the
expectations to the relative URLs the helper now produces.

Co-authored-by: Ibrahim Khan <ibrakhxn@amazon.com>

packages/ui/src/lib/gitApiHttp.test.ts

@@ -56,7 +56,7 @@ describe('gitApiHttp index mutations', () => {
       await stageGitFiles('/repo', ['a.ts', 'b.ts']);
 
       expect(calls).toHaveLength(1);
-      expect(String(calls[0].input)).toBe('http://localhost:3000/api/git/stage?directory=%2Frepo');
+      expect(String(calls[0].input)).toBe('/api/git/stage?directory=%2Frepo');
       expect(calls[0].init?.method).toBe('POST');
       expect(JSON.parse(String(calls[0].init?.body))).toEqual({ paths: ['a.ts', 'b.ts'] });
     } finally {
@@ -71,7 +71,7 @@ describe('gitApiHttp index mutations', () => {
       await unstageGitFiles('/repo', ['a.ts', 'b.ts']);
 
       expect(calls).toHaveLength(1);
-      expect(String(calls[0].input)).toBe('http://localhost:3000/api/git/unstage?directory=%2Frepo');
+      expect(String(calls[0].input)).toBe('/api/git/unstage?directory=%2Frepo');
       expect(calls[0].init?.method).toBe('POST');
       expect(JSON.parse(String(calls[0].init?.body))).toEqual({ paths: ['a.ts', 'b.ts'] });
     } finally {