SOLR-17715: Remove "qt" param path support in SolrJ

[r4mercur]

https://issues.apache.org/jira/browse/SOLR-17715

Related pull requests before: #3441
For transparency i used claude code and github copilot for recommendations.

Description

Please provide a short description of the changes you're making with this pull request.

Solution

Proposed solution changes in QueryRequest.java file.

1. getPath() override is removed
2. QueryRequest() no-argument sets /select as default to super() method
3. QueryRequests() with SolrParams and with Params and Method extract the qt in the constructor like recommended by dsmiley.
4. 2 new constructors with path and params & one with path, params and method.
5. two helper methods

Tests

Test cases which are added:
in class QueryRequestTest.java

1. testQtWithSlashBecomesPath: qt=/custom no qt in params
2. testQtWithoutSlashDefaultsToSelect: qt=custom no path = /select path
3. testDefaultPathToSelect: no qt param = default path /select

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
• I have added a changelog entry for my change

[dsmiley]

Looks good; thanks!
I was gonna mention deprecating the other constructors but no... they are fine. After all, it's common to rely on a /select default.
I do think the no-arg constructor is weird/useless.