Fix logging when an OFF connection initializes first - #1670

Description

Fix process-wide JUL initialization when the first connection uses LogLevel=OFF.

• OFF suppresses the shared parent logger without creating a handler or permanently completing initialization.
• The first logging-enabled connection installs the single shared handler.
• Once enabled, later connections—including OFF connections—do not reconfigure the logger.
• Failed handler creation remains retryable.

Testing

• Unit tests cover OFF -> TRACE, TRACE -> OFF, concurrent initialization without duplicate handlers, and retry after failed handler creation.
• JulLoggerTest and LoggingUtilTest: 30 tests passed.
• Thin and uber JARs were manually verified: OFF -> TRACE creates one handler, while TRACE -> OFF retains the original handler and level.

Additional Notes to the Reviewer

This is the short-term fix and intentionally keeps handler creation inside JulLogger.initLogger().