[llvm] [bazel] Flip --enable_bzlmod to true (PR #168555)

[Jordan Rupprecht via llvm-commits]

rupprecht wrote:

> This is harmless since downstream repos shouldn't inherit this bazelrc setting. The last PR is the one that would affect folks

Ah, didn't realize that :)

In that case, I guess I might as well land this now?

The next step after this would be to delete the WORKSPACE file. Do you know what downstream things, if anything, we would need to wait for before deleting that?

https://github.com/llvm/llvm-project/pull/168555