rfcomm_cback: Reduce congestion event log levels

- Move logs to individual cases for more control over log levels
- Set congestion and write events to verbose to avoid spam; all others
  set to info

Bug: 329507884
Test: m Bluetooth
Test: Manual - send data between phones and verify log levels are
appropriate
Flag: EXEMPT log changes only
Change-Id: I28ff48f93fe64d2bd1bf2e195da376d85885925c

Change-Id: Ib1e7e36ad288696437df3a6b7b82d229e6ac4b3c