osd: provide fmtlib formatter for ScrubMapBuilder

Signed-off-by: Ronen Friedman <rfriedma@redhat.com>

Merge pull request #66230 from ronen-fr/wip-rf-larger-stride

osd/scrub: increasing the default data-read stride

Reviewed-by: Radoslaw Zarzynski <rzarzyns@redhat.com>
Reviewed-by: Anthony D'Atri <anthony.datri@gmail.com>
Reviewed-by: Alex Ainscow <aainscow@uk.ibm.com>
Reviewed-by: Jon Bailey <jonathan.bailey1@ibm.com>

Merge pull request #64248 from zhuwei127/fix-doublefree

examples/librados: fix memory pointed to by 'rs' is freed twice.

Reviewed-by: Patrick Donnelly <pdonnell@ibm.com>

common/options: document osd_deep_scrub_stride

default value change (from 0.5MB to 4MB)

Signed-off-by: Ronen Friedman <rfriedma@redhat.com>

qa/standalone: osd-scrub-dump.sh: test large object scrubs

following a change to the default stride size for deep scrubs,
adding a standalone test to verify that scrubs of large objects
work correctly (and to perform some minimal performance
measurements).

Signed-off-by: Ronen Friedman <rfriedma@redhat.com>

osd/scrub: increasing the default data-read stride

When performing deep scrubs, the scrubber reads object
data in strides, to avoid monopolizing the OSD's I/O capacity.
The default stride was set to 0.5MB, which is too low for
modern storage devices. This commit increases the default
stride to 4MB.

Signed-off-by: Ronen Friedman <rfriedma@redhat.com>