feat: Remove the verifySubscription() function when starting CPS source connector

[rQ-Qrr]

Fixes #383 ☕️

[matt-kwong]

Please update the commit message to follow the convention.

The change makes sense to me. Could you include a before and after of how the connector handles a non-existent subscription on startup?

[rQ-Qrr]

Please update the commit message to follow the convention.

Sure, updated.

Could you include a before and after of how the connector handles a non-existent subscription on startup?

Before, if the subscription doesn't exist, when creating the CPS source connector, it will return an error org.apache.kafka.connect.errors.ConnectException: Error verifying the subscription cps-source-topic-sub for project and the status of the CPS source connector is failed.

After this change, it still returns an error com.google.api.gax.rpc.NotFoundException: com.google.api.gax.rpc.NotFoundException: io.grpc.StatusRuntimeException: NOT_FOUND: Resource not found (resource=cps-source-topic-sub).. However, the status of the CPS source connector won't become failed but keep as Running.

[pradn]

After this change, it still returns an error com.google.api.gax.rpc.NotFoundException: com.google.api.gax.rpc.NotFoundException: io.grpc.StatusRuntimeException: NOT_FOUND: Resource not found (resource=cps-source-topic-sub).. However, the status of the CPS source connector won't become failed but keep as Running.

We actually do want the connector to go into a Failed state if it subscribing from a CPS Subscription returns NotFound. A NotFound error like this requires user intervention. PTAL

The only reason we're removing the check at startup is to reduce the number of permissions required to run the connector - just subscriptions.consume, not subscriptions.get. Everything else should stay the same, I believe.