Make git.OpenRepository accept Context (#19260)

* OpenRepositoryCtx -> OpenRepository
* OpenRepository -> openRepositoryWithDefaultContext, only for internal usage

services/gitdiff/gitdiff_test.go

@@ -690,7 +690,7 @@ func TestDiffLine_GetCommentSide(t *testing.T) {
 }
 
 func TestGetDiffRangeWithWhitespaceBehavior(t *testing.T) {
-	gitRepo, err := git.OpenRepository("./testdata/academic-module")
+	gitRepo, err := git.OpenRepository(git.DefaultContext, "./testdata/academic-module")
 	if !assert.NoError(t, err) {
 		return
 	}