Generated code fails with undefined: longrunning.InternalNewOperationWithMetadata

I ran `librarian generate -all` with the latest googleapis SHA and the Kokoro build failed: https://fusion2.corp.google.com/invocations/13075e79-e911-4147-84cf-d118932abdaf/log :

```
+ gotestsum --packages=./... --junitfile sponge_log.xml --format standard-verbose -- -race --short --timeout 15m
go: downloading [cloud.google.com/go/longrunning](http://cloud.google.com/go/longrunning) v0.9.0
? [cloud.google.com/go/cloudtasks/apiv2/cloudtaskspb](http://cloud.google.com/go/cloudtasks/apiv2/cloudtaskspb) [no test files]
testing: warning: no tests to run
PASS
? [cloud.google.com/go/cloudtasks/apiv2beta2/cloudtaskspb](http://cloud.google.com/go/cloudtasks/apiv2beta2/cloudtaskspb) [no test files]
testing: warning: no tests to run
PASS
ok [cloud.google.com/go/cloudtasks/apiv2](http://cloud.google.com/go/cloudtasks/apiv2) 1.046s [no tests to run]
FAIL [cloud.google.com/go/cloudtasks/apiv2beta3](http://cloud.google.com/go/cloudtasks/apiv2beta3) [build failed]
? [cloud.google.com/go/cloudtasks/apiv2beta3/cloudtaskspb](http://cloud.google.com/go/cloudtasks/apiv2beta3/cloudtaskspb) [no test files]
? [cloud.google.com/go/cloudtasks/internal](http://cloud.google.com/go/cloudtasks/internal) [no test files]
ok [cloud.google.com/go/cloudtasks/apiv2beta2](http://cloud.google.com/go/cloudtasks/apiv2beta2) 1.030s [no tests to run]

=== Failed
=== FAIL: apiv2beta3 (0.00s)
FAIL [cloud.google.com/go/cloudtasks/apiv2beta3](http://cloud.google.com/go/cloudtasks/apiv2beta3) [build failed]

=== Errors
[apiv2beta3/cloud_tasks_client.go:1477](https://cs.corp.google.com/piper///depot/google3/apiv2beta3/cloud_tasks_client.go?l=1477):21: undefined: longrunning.InternalNewOperationWithMetadata

[apiv2beta3/cloud_tasks_client.go:1527](https://cs.corp.google.com/piper///depot/google3/apiv2beta3/cloud_tasks_client.go?l=1527):21: undefined: longrunning.InternalNewOperationWithMetadata

[apiv2beta3/cloud_tasks_client.go:2781](https://cs.corp.google.com/piper///depot/google3/apiv2beta3/cloud_tasks_client.go?l=2781):21: undefined: longrunning.InternalNewOperationWithMetadata

[apiv2beta3/cloud_tasks_client.go:2901](https://cs.corp.google.com/piper///depot/google3/apiv2beta3/cloud_tasks_client.go?l=2901):21: undefined: longrunning.InternalNewOperationWithMetadata

[apiv2beta3/cloud_tasks_client.go:3341](https://cs.corp.google.com/piper///depot/google3/apiv2beta3/cloud_tasks_client.go?l=3341):20: undefined: longrunning.InternalNewOperationWithMetadata

[apiv2beta3/cloud_tasks_client.go:3350](https://cs.corp.google.com/piper///depot/google3/apiv2beta3/cloud_tasks_client.go?l=3350):25: undefined: longrunning.InternalNewOperationWithMetadata

[apiv2beta3/cloud_tasks_client.go:3359](https://cs.corp.google.com/piper///depot/google3/apiv2beta3/cloud_tasks_client.go?l=3359):20: undefined: longrunning.InternalNewOperationWithMetadata

[apiv2beta3/cloud_tasks_client.go:3368](https://cs.corp.google.com/piper///depot/google3/apiv2beta3/cloud_tasks_client.go?l=3368):25: undefined: longrunning.InternalNewOperationWithMetadata
```

_Originally posted by @suztomo in https://github.com/googleapis/google-cloud-go/issues/20188#issuecomment-5049775934_