compaction_backlog_tracker: Raise logging level to error when disabling tracker on exception
compaction_backlog_tracker: Raise logging level to error when disabling tracker on exception

If exception is caught while updating backlog tracker, the backlog
tracker will be disabled for the underlying table, potentially
causing compaction to fall behind.
That being said, let's raise the log level to error, to give it
its due importance and allow tests to detect the problem.

Signed-off-by: Raphael S. Carvalho <1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@scylladb.com>
Message-Id: <20220330151421.49054-1-1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla