mgr/telemetry: collect what we can from heap stats, mempools, and osd histograms

mgr/telemetry: collect what we can from heap stats, mempools, and osd histograms

If we run into a problem collecting heap stats, mempools,
or osd histograms from a particular osd (i.e. the osd is down),
we should continue to collect what we can from other osds rather
than exiting and returning an empty JSON object.

Some log messages are also refined.

Fixes: https://tracker.ceph.com/issues/53985
Signed-off-by: Laura Flores <lflores@redhat.com>
(cherry picked from commit c617b78f7bb589314b3c377496a9bb3914cbb2ba)