Remove Bazel related files

[Zerpet]

Is your feature request related to a problem? Please describe.

Bazel is not used anymore to build RabbitMQ in main and 4.x branches.

Describe the solution you'd like

Remove Bazel related files.

Additional context

Bazel has served us well for what it was originally chosen for: parallel and partial test runs. But with the current team it does not look as attractive and so we stick to Make.

Kudos to @michaelklishin for recognising the great value that Bazel provided to our team for years.