SOLR-17453: Drop CloudUtil.waitForState() in favor of common waitForState()

[psalagnac]

https://issues.apache.org/jira/browse/SOLR-17453
(this does not fully address the ticket)

Description

Method CloudUtil.waitForState() does use a Zookeeper watch, but it does active polling of the collection state. This change is in test code only.

Solution

Update tests so they use the standard waitForState(), relying on a Zookeeper watch, instead of actively polling the collection state.

I removed method CloudUtil.waitForState().

Also removed CloudUtil.clusterShape() as it is unused. The correct one is in SolrCloudTestCase and already used everywhere. This makes test code a little less bloated.

Tests

This change is in only test code.

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended, not available for branches on forks living under an organisation)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide

[dsmiley]

Assuming tests seem stable, I plan to merge this PR. I like that it's focused on one thing. No CHANGES.txt as there was only test changes. Another PR can address other aspects of SOLR-17453.