bug: Investigate and re-enable disabled benchmark tests

The following benchmark tests are currently disabled in the macOS Kokoro CI build:

- `//generator/integration_tests:benchmarks_client_benchmark`
- `//google/cloud:options_benchmark`

These tests were disabled in `ci/kokoro/macos/builds/bazel.sh` to resolve CI failures and stabilize the build.

This issue tracks the work to:
1. Investigate the root cause of the failures in these benchmarks.
2. Fix the underlying issues.
3. Re-enable the tests by removing them from the `BAZEL_TEST_EXCLUDES` list in the `ci/kokoro/macos/builds/bazel.sh` script.

从已命名的两个基准测试目标开始，检查它们在 ci/kokoro/macos/builds/bazel.sh 中的排除情况，尤其是 BAZEL_TEST_EXCLUDES 列表。重现 macOS Kokoro 失败，并调查其根本原因。完成的标准是修复底层问题、从排除列表中移除两个基准测试，并且 macOS CI 构建通过。

由索引模型根据 Issue 内容生成。