Remove duplicated debug logging around locking

Remove duplicated debug logging around locking

Currently, iptables_manager.py does extra unnecessary logging about lock
acquisition and release. It uses lockutils.lock() which passes
do_log=True by default, which causes lockutils.lock() to do debug
logging about lock acquisition/release. IptablesManager itself also writes
debug log info about lock acquisition and release.

This change will eliminate unnecessary duplicate logging in order to
reduce log noise about locking. This change is also related to
https://github.com/harlowja/fasteners/commit/f88f2fea7fe250b7d26cdcbc84633ccbbc68eeee
which reduces the logging level in the underlying lock implementation
used by oslo.concurrency. That change along with this one will remove
the duplicate debug logging about locking in iptables_manager.py and also in
ipset_manager.py.

Change-Id: If6f4a7101f3783ad83645e28bbb5c577dd403d3b
Closes-Bug: 1464727