Snippet Gen: Prevent namespace collisions with Google\Rpc\Status

I have yet to find any cases where this happens, but it would be good to safeguard against.

LRO based samples import `Google\Rpc\Status` and reference it by relative name of `Status`. It is possible for this relative name to conflict with an import for a generated proto class, (ex. `Google\Cloud\Service\Status`). Options to address this can be to use an alias or the FQNS for samples where a conflict may arise.

Reference: https://github.com/googleapis/gapic-generator-php/blob/main/tests/Unit/ProtoTests/BasicLro/out/samples/BasicLroClient/method1.php#L59