doc/radosgw/config-ref: fix lc worker thread tuning

doc/radosgw/config-ref: fix lc worker thread tuning

This commit updates RGW Config Reference - Lifecycle Settings section. In particular it addresses an incorrect suggestion to decrease parallel threads in the workers pool for a more aggressive/accelerated per-bucket lifecycle processing. A more aggressive lifecycle processing for a bucket containing higher number of objects is achieved by increasing, not decreasing parallel threads.
Current suggestion is miss-leading.

Fixes: https://tracker.ceph.com/issues/63659
Signed-off-by: Laimis Juzeliunas <laimis.juzeliunas@oxylabs.io>
(cherry picked from commit b7ae18a292c7d1d5139dfb74c575f1af0de29a3e)