test/gitindex: assert clone URL changes no longer rewrite remote origin

After removing remote.origin.url sync from existing-clone updates, keep an explicit regression check that captures the behavior boundary.

The integration test now changes the clone URL during a metadata update and verifies remote.origin.url remains at the originally cloned value while zoekt config still updates and triggers a destination return.

Test Plan: go test ./...

Amp-Thread-ID: https://ampcode.com/threads/T-019d0c05-51b0-77ee-a1dc-cb60ce14712d
Co-authored-by: Amp <amp@ampcode.com>

Author: keegancsmith

gitindex/clone_test.go

@@ -85,7 +85,9 @@ func gitConfigValue(t *testing.T, repoDir, key string) (string, bool) {
 func TestCloneRepoUpdatesExistingSettings(t *testing.T) {
 	root := t.TempDir()
 	originA := filepath.Join(root, "origin-a.git")
+	originB := filepath.Join(root, "origin-b.git")
 	runScript(t, root, "git init --bare "+originA)
+	runScript(t, root, "git init --bare "+originB)
 
 	destRoot := filepath.Join(root, "repos")
 	repoDest := filepath.Join(destRoot, "owner", "repo.git")
@@ -112,7 +114,7 @@ func TestCloneRepoUpdatesExistingSettings(t *testing.T) {
 		t.Fatalf("got %q want empty destination for unchanged settings", dest)
 	}
 
-	dest, err = CloneRepo(destRoot, "owner/repo", originA, map[string]string{
+	dest, err = CloneRepo(destRoot, "owner/repo", originB, map[string]string{
 		"zoekt.name":        "github.com/owner/repo",
 		"zoekt.description": "",
 	})