SOLR-16503: Introduce new default Http2SolrClient in UpdateShardHandler

[iamsanjay]

https://issues.apache.org/jira/browse/SOLR-16503

Currently default HTTP (Apache Http 1) client in UpdateShardHandler is being used at many places in the codebase and consequently removing it at once and replacing with Jetty HTTP2 would requires lots of efforts and testing. Instead, the possibility of introducing another default Jetty HTTP2 client in UpdateShardHandler is proposed to facilitate incremental changes.

Checklist

Please review the following and check all that apply:

• [x] I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• [x] I have created a Jira issue and added the issue ID to my pull request title.
• [x] I have given Solr maintainers access to contribute to my PR branch. (optional but recommended)
• [x] I have developed this patch against the main branch.
• [x] I have run ./gradlew check.
• [ ] I have added tests for my changes.
• [ ] I have added documentation for the Reference Guide

[epugh]

@iamsanjay anythingbi can do to help get this in? Some great work here!!!

[github-actions[bot]]

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