Fix CI breakages for release-6.2.0

- Remove pinned Xcode version, due to recent CI infrastructure change, Xcode 13.0 is no longer available.
- Disable GitRepositoryBlackBoxTest

.bazelci/postsubmit.yml

@@ -158,7 +158,6 @@ tasks:
       - build
       - test
   macos:
-    xcode_version: "13.0"
     shell_commands:
       - sed -i.bak -e 's/^# android_sdk_repository/android_sdk_repository/' -e 's/^#
         android_ndk_repository/android_ndk_repository/' WORKSPACE
@@ -214,6 +213,8 @@ tasks:
       - "-//src/test/java/com/google/devtools/build/lib/platform:SystemMemoryPressureEventTest"
       # https://github.com/bazelbuild/bazel/issues/17411
       - "-//src/test/java/com/google/devtools/build/lib/blackbox/tests/workspace:PatchApiBlackBoxTest"
+      # https://github.com/bazelbuild/bazel/issues/17447
+      - "-//src/test/java/com/google/devtools/build/lib/blackbox/tests/workspace:GitRepositoryBlackBoxTest"
     include_json_profile:
       - build
       - test

.bazelci/presubmit.yml

@@ -148,7 +148,6 @@ tasks:
       # Re-enable once fixed: https://github.com/bazelbuild/bazel/issues/8162
       - "-//src/java_tools/import_deps_checker/..."
   macos:
-    xcode_version: "13.0"
     shards: 5
     shell_commands:
       - sed -i.bak -e 's/^# android_sdk_repository/android_sdk_repository/' -e 's/^#
@@ -207,6 +206,8 @@ tasks:
       - "-//src/test/java/com/google/devtools/build/lib/platform:SystemMemoryPressureEventTest"
       # https://github.com/bazelbuild/bazel/issues/17411
       - "-//src/test/java/com/google/devtools/build/lib/blackbox/tests/workspace:PatchApiBlackBoxTest"
+      # https://github.com/bazelbuild/bazel/issues/17447
+      - "-//src/test/java/com/google/devtools/build/lib/blackbox/tests/workspace:GitRepositoryBlackBoxTest"
   windows:
     shards: 4
     batch_commands: