Cleanup Bazel workarounds for gRPC and `apple_rules`

[coryan]

gRPC 1.60.x does not compile out of the box with Bazel v7. Bazel v7 requires a newer version of apple_rules than what gRPC uses.

We can override the version of apple_rules, but that requires some careful initialization of the C++ toolchain.

Alternatively, it would be nice if gRPC did not require these rules when compiling only C++ targets.

None of these things are true now, but once either becomes true we can remove the code overriding and initializing apple_rules from our project.

[scotthart]

Need to check if gRPC has resolved their portion of this issue.