Add post create 5s sleep to Topic creation

[jessdejong]

Description: Adding a post_create sleep time of 5 seconds to the Managed Service for Apache Kafka terraform Topic resource.

Issue: https://buganizer.corp.google.com/issues/357620880

managedkafka: added 5 second wait post `google_managed_kafka_topic` creation to fix eventual consistency errors 

[github-actions]

Hello! I am a robot. Tests will require approval from a repository maintainer to run.

@ScottSuarez, a repository maintainer, has been assigned to review your changes. If you have not received review feedback within 2 business days, please leave a comment on this PR asking them to take a look.

You can help make sure that review is quick by doing a self-review and by running impacted tests locally.

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

google-beta provider: Diff ( 1 file changed, 5 insertions(+))

[modular-magician]

Tests analytics

Total tests: 5
Passed tests: 5
Skipped tests: 0
Affected tests: 0

Click here to see the affected service packages

• managedkafka

$\textcolor{green}{\textsf{All tests passed!}}$

View the build log

[ScottSuarez]

closes hashicorp/terraform-provider-google#18949