Set Xcode version to 15.1 on macOS arm64 machines
bazel_determinism_test seems to be flaky due to an non-determinsitc
issue of the clang compiler in Xcode 14.2

Fixes https://github.com/bazelbuild/bazel/issues/20690

PiperOrigin-RevId: 598760276
Change-Id: Ibc46dfa64fe91f26acfa5091a07c17e3bf97f29c

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Allow network for two Java tests to avoid binding issue on macOS sandbox

https://buildkite.com/bazel/bazel-bazel/builds/26312#018d1722-0e79-47b4-82ed-9cc47487e05a

Related issues:
- https://github.com/bazelbuild/bazel/issues/20743
- https://github.com/bazelbuild/bazel/issues/5206

PiperOrigin-RevId: 599452705
Change-Id: I2fdccd9df513064e5bc9add4f1802d4c1ce9c6da

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Allow network for StarlarkDebugServerTest
Related issues:
- https://github.com/bazelbuild/bazel/issues/20743
- https://github.com/bazelbuild/bazel/issues/5206

PiperOrigin-RevId: 599754818
Change-Id: I228201d578b7459332aebfea6ab4d7c041b3e6c4

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Add mirror for embedded JDKs URLs
Reduce flakiness like:
https://buildkite.com/bazel/bazel-bazel/builds/26343#018d1e09-4c23-404c-a307-7476e092c7ab

PiperOrigin-RevId: 599759327
Change-Id: I43fa2ec996f03e77da926c2afeaca13cbf029a1b