Bazel had the dependency added because of #5046, where Guava was
depending on it as compile-only and Bazel build have "unknown enum
constant" warnings. Guava now has a compile dependency on j2objc, so
this workaround is no longer needed. There are currently no version skew
issues in Gradle, which was the only usage.
The recommended way to load dependencies from `rules_jvm_external`
is to make use of the `@maven` workspace, and the most readable
way of doing that is to use the `artifact` macro provides.
This removes the need to generate the "compat" namespaces, which
`rules_jvm_external` provided for backwards compatibility with
older releases. This change also sets things up for supporting
`bzlmod`: this requires all workspaces accessed by a library to
be named "up front" in the `MODULE.bazel` file. This way, the
only repo that needs to be exported is `@maven`, rather than the
current huge list.