refactor: fix verbose env var bug and simplify codebase

[KyleCB]

Summary

Fix a bug where NewVerbose() reads BPL_JAVA_NMT_ENABLED instead of BP_LOG_LEVEL, making verbose mode non-functional via env var. Also includes several cleanups found during review.

Use Cases

• Setting BP_LOG_LEVEL=DEBUG now correctly enables verbose output as documented
• JVMCacerts.Contribute() no longer has a TOCTOU race between existence check and env var assignment
• BuildJavaToolOptions() correctly deduplicates options by token instead of substring, preventing false positives
• SpringOptimizer.Execute() no longer allocates an unnecessary map and slice to dispatch a single helper
• buildHelpers() in Calculator skips constructing OpenSSLCertificateLoader and NMT when their respective flags are disabled, rather than building them and immediately deleting them from the map

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).