chore: suppress tests from logging for clearer failures

[BryceARich]

Before:

bundle exec rake
Running RuboCop...
Inspecting 15 files
...............

15 files inspected, no offenses detected
Run options: --seed 15607

# Running:

.....................2025-08-01 14:57:49.578008 E [48126:1032 nats_api_server.rb:217]  -- Error processing message:  -- fail
2025-08-01 14:57:49.578387 E [48126:1032 nats_api_server.rb:200]  -- Error processing message:  -- Exception: RuntimeError: boom
<Long nasty stack trace that looks like failing tests>

After:

bundle exec rake
Running RuboCop...
Inspecting 15 files
...............

15 files inspected, no offenses detected
Run options: --seed 13131

# Running:

.....................

Finished in 0.000816s, 25735.2891 runs/s, 23284.3092 assertions/s.

21 runs, 19 assertions, 0 failures, 0 errors, 0 skips

[Copilot]

Pull Request Overview

This PR suppresses log output during test execution to provide cleaner test failure reporting. The change prevents verbose logging from cluttering the test output, making it easier to identify actual test failures.

• Adds logging suppression configuration to the test helper
• Sets SemanticLogger default level to :fatal to hide lower-level log messages during tests