mgr/DaemonServer: Limit search for OSDs to upgrade within the crush bucket.

mgr/DaemonServer: Limit search for OSDs to upgrade within the crush bucket.

The behavior of the 'ok-to-upgrade' command is now more deterministic with
respect to the parameters passed.

To achieve the above, the commit implements the following changes:

1. The 'ok-to-upgrade' command is modified to operate strictly on the OSDs
   within the CRUSH bucket and, if possible, meet the '--max' criteria when
   specified. When --max <num> is provided, the command returns up to <num>
   OSD IDs from the specified CRUSH bucket that can be safely stopped for
   simultaneous upgrade. This is useful when only a subset of OSDs within
   the bucket needs to be upgraded for performance or other reasons.

2. Modifies the standalone tests to reflect the above change.

3. Modifies the relevant documentation to reflect the change in behavior.

Fixes: https://tracker.ceph.com/issues/75681
Signed-off-by: Sridhar Seshasayee <sridhar.seshasayee@ibm.com>