Remove protobuf rust from BCR presubmits for now.

Rust protobuf is in development and not intended for use / released yet. We should add this back at some point when rust is ready for release, after adding equivalent GHA presubmit tests.

PiperOrigin-RevId: 653252995

Author: zhangskz

.bcr/presubmit.yml

@@ -14,7 +14,6 @@ tasks:
     - '@protobuf//:protobuf'
     - '@protobuf//:protobuf_lite'
     - '@protobuf//:protobuf_python'
-    - '@protobuf//:protobuf_rust'
     - '@protobuf//:protoc'
     - '@protobuf//:test_messages_proto2_cc_proto'
     - '@protobuf//:test_messages_proto3_cc_proto'