bazelbuild/bazel@fe85936

Otherwise, integration tests fail with
```
ERROR: /tmp/bazel-working-directory/_main/bazel-out/k8-fastbuild/bin/zig/tests/integration_tests/zig_version_test_0.11.0.runfiles/_main/zig/tests/integration_tests/workspace/BUILD.bazel:13:11: Building main.zig as Zig binary bazel-out/k8-fastbuild/bin/binary failed: (Exit 1): zig failed: error executing ZigBuildExe command (from target //:binary) external/rules_zig~override~zig~zig_x86_64-linux/zig build-exe '-femit-bin=bazel-out/k8-fastbuild/bin/binary' main.zig --zig-lib-dir external/rules_zig~override~zig~zig_x86_64-linux/lib --cache-dir ... (remaining 8 arguments skipped)

Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
external/rules_zig~override~zig~zig_x86_64-linux/lib/std/std.zig:106:22: error: unable to load 'main.zig': NotDir
```

Captures the builtin bzl files in a version independent way.

The lock file format changed between Bazel 6.3.0 and 7.0.0rc4. However,
we're testing both Bazel versions on CI. So, one will fail on the
other's lock file.

The documentation can vary between Bazel versions. E.g. Bazel 7 changed
the documentation of the implicit `repo_mapping` parameter to repository
rules.

Hence, we need to disable docs generation and in particular tests when
testing against other Bazel versions than the main development version.

See bazelbuild/bazel#19493