Generator adds iterator.Done check where iterator is not defined in gapic-showcase

[aandreassa]

The go_cli plugin is incorrectly adding a code block to check for iterator.Done in the generated file cmd/gapic-showcase/search-blurbs.go. This causes a compilation error because the iterator variable is not defined in that context. This is only an issue for that specific file.

PR reproducing the issue: googleapis/gapic-showcase#1597

Steps to reproduce

1. Updated dependencies as shown in feat: update dependencies and regenerate clients gapic-showcase#1597
2. Followed steps in for regenerating
3. Code doesn't compile due to iterator variable.