Merge pull request #18771 from jtattermusch/cleanup_rbe_builds

tools/internal_ci/linux/grpc_bazel_rbe_asan.cfg

tools/internal_ci/linux/grpc_bazel_rbe_dbg.cfg

...internal_ci/linux/grpc_bazel_rbe_incompatible_changes.cfg

tools/internal_ci/linux/grpc_bazel_rbe_msan.cfg

tools/internal_ci/linux/grpc_bazel_rbe_opt.cfg

tools/internal_ci/linux/grpc_bazel_rbe_tsan.cfg

tools/internal_ci/linux/grpc_bazel_rbe_ubsan.cfg

tools/internal_ci/linux/pull_request/grpc_bazel_rbe_asan.cfg

tools/internal_ci/linux/pull_request/grpc_bazel_rbe_dbg.cfg

tools/internal_ci/linux/pull_request/grpc_bazel_rbe_msan.cfg

tools/internal_ci/linux/pull_request/grpc_bazel_rbe_opt.cfg

tools/internal_ci/linux/pull_request/grpc_bazel_rbe_tsan.cfg

...s/internal_ci/linux/pull_request/grpc_bazel_rbe_ubsan.cfg

tools/internal_ci/windows/grpc_bazel_rbe_dbg.cfg