doc/rados: Fix Sphinx warnings in troubleshooting/log-and-debug.rst

doc/rados: Fix Sphinx warnings in troubleshooting/log-and-debug.rst

Possibly controversial Sphinx fixes:

Fix two Sphinx warnings about more than one confval directive.
Remove the dupe confval directives from log-and-debug.rst and leave only
in mon-config-ref.rst because it has the only copy of a related clog
configuration value mon_health_to_clog_tick_interval.

Signed-off-by: Ville Ojamo <14869000+bluikko@users.noreply.github.com>