chore: remove unused proto imports (#96)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 468735472

Source-Link: googleapis/googleapis@cfa1b37

Source-Link: googleapis/googleapis-gen@09b7666
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiMDliNzY2NjY1NjUxMGY1YjAwYjg5M2YwMDNhMGJhNTc2NmY5ZTI1MCJ9

Author: gcf-owl-bot[bot]

packages/google-cloud-privatecatalog/protos/google/cloud/privatecatalog/v1beta1/private_catalog.proto

@@ -21,9 +21,6 @@ import "google/api/client.proto";
 import "google/api/field_behavior.proto";
 import "google/api/resource.proto";
 import "google/longrunning/operations.proto";
-import "google/protobuf/any.proto";
-import "google/protobuf/empty.proto";
-import "google/protobuf/field_mask.proto";
 import "google/protobuf/struct.proto";
 import "google/protobuf/timestamp.proto";