Flag --incompatible_disable_starlark_host_transitions will break Bazel Remote Cache in Bazel 7.0

[keertk]

Incompatible flag --incompatible_disable_starlark_host_transitions will be enabled by default in the next major release (Bazel 7.0), thus breaking Bazel Remote Cache. Please migrate to fix this and unblock the flip of this flag.

The flag is documented here: bazelbuild/bazel#17032.

Please check the following CI builds for build and test results:

• MacOS OpenJDK 11
• Ubuntu 18.04 OpenJDK 11
• Ubuntu 20.04 OpenJDK 11

Never heard of incompatible flags before? We have documentation that explains everything.
If you have any questions, please file an issue in https://github.com/bazelbuild/continuous-integration.

[mostynb]

I guess this requires a rules_docker update:

(10:19:12) ERROR: Traceback (most recent call last):
	File "/var/lib/buildkite-agent/.cache/bazel/_bazel_buildkite-agent/7d02f004d35201206c9844fcbbd1783b/external/io_bazel_rules_docker/toolchains/docker/toolchain.bzl", line 63, column 39, in <toplevel>
		"build_tar_target": attr.label(
Error in label: 'cfg = "host"' is deprecated and should no longer be used. Please use 'cfg = "exec"' instead.
(10:19:12) ERROR: Error computing the main repository mapping: at /var/lib/buildkite-agent/.cache/bazel/_bazel_buildkite-agent/7d02f004d35201206c9844fcbbd1783b/external/io_bazel_rules_docker/repositories/repositories.bzl:22:5: initialization of module 'toolchains/docker/toolchain.bzl' failed

[mostynb]

Filed bazelbuild/rules_docker#2196 to try to fix this upstream.