Remove legacy ClientConfiguration code

[ctubbsii]

• Delete ClientConfiguration and unit test
• Update ClientConfConverter to remove legacy client config
• Update ClientConfConverterTest.basic to test conversion directly to/from client Properties and AccumuloConfiguration (which is still needed for some bootstrapping code and SASL configuration code)
• Remove legacy trace props from ClientProperty
• Remove deprecated getClientConfig() methods from minicluster
• No longer write out client config file (only client properties file) and no longer set corresponding ACCUMULO_CLIENT_CONF_PATH environment variable for minicluster
• Update SaslServerConnectionParams to remove unused overloaded constructors and setters (allowing secretManager field to be final); this wasn't strictly necessary in this patch, but helped simplify things to make it easier to trace the uses of the ClientConfConverter methods to see how they were still needed

[EdColeman]

LGTM - looks like there is additional work needed for the tests to pass though

[ctubbsii]

This was very frustrating code to clean up, but I'm confident I've fixed the earlier bugs. I've already confirmed all the hung and failing tests from the first pass are fixed, but I will re-run the full ITs to be sure there's nothing else.

[ctubbsii]

Full ITs finished successfully. Seems unrelated, but saw SaslConnectionParamsTest was a bit flaky in GitHub Actions. I forced it to run in a separate JVM fork from other tests, because it always worked for me when running on its own, so it seems likely another test in the same JVM was interfering with it.