doc: Use validated links with ref instead of external links

Use :ref: for intra-docs links that are validated, instead of external
links.
Only use already existing labels.
Fixes a few anchors that pointed to now-renamed section titles.
Use automatically generated link text where appropriate.
Delete unused link definitions.

Mostly in doc/rados/ but also a few in doc/rbd/.
Try to fix all links in each of the changed documents.

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

Merge pull request #66489 from joscollin/wip-drop-double-check

mds: drop checking CEPH_MDS_OP_SETLAYOUT two times

Reviewed-by: Patrick Donnelly <pdonnell@ibm.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>

Merge pull request #66158 from xxhdx1985126/wip-seastore-minor-perf-issue

crimson/os/seastore/epm: avoid unnecessary container copies

Reviewed-by: Matan Breizman <mbreizma@redhat.com>
Reviewed-by: Samuel Just <sjust@redhat.com>

mds: drop checking CEPH_MDS_OP_SETLAYOUT two times

Signed-off-by: Jos Collin <jcollin@redhat.com>

Merge pull request #65773 from trociny/wip-69492

rbd-mirror: add cluster fsid to remote meta cache key

Reviewed-by: Ilya Dryomov <idryomov@gmail.com>