CASSSIDECAR-418: RangeManager "localDC is unavailable" very early upon Sidecar startup

[arvindKandpal-ksolves]

RangeManager called initializeRanges() in its constructor. The constructor runs during Guice injection, before Sidecar connects to Cassandra, so with CDC enabled every startup logged "localDC is unavailable" with a full stack trace and "DC null, cannot initialize owned ranges".

Changes:

• Remove the call from the constructor. Ranges are still set on ON_CASSANDRA_CQL_READY.
• Log the localDC failure at WARN without the stack trace. The stack trace now goes to DEBUG.
• Add RangeManagerTest.

Testing:

• Reproduced the error on trunk. It is gone after the fix.
• Against Cassandra 4.1, ranges are set after CQL connects, with no errors.
• RangeManagerTest, CdcManagerTest, CdcPublisherTests and ClusterTopologyMonitorTest pass, and checkstyle passes.

[arvindKandpal-ksolves]

cc @yifan-c @frankgh @bbotella