md/md-cluster: handle REMOVE message earlier

md/md-cluster: handle REMOVE message earlier

Commit a1fd37f97808 ("md: Don't wait for MD_RECOVERY_NEEDED for
HOT_REMOVE_DISK ioctl") introduced a regression in the md_cluster
module. (Failed cases 02r1_Manage_re-add & 02r10_Manage_re-add)

Consider a 2-node cluster:
- node1 set faulty & remove command on a disk.
- node2 must correctly update the array metadata.

Before a1fd37f97808, on node1, the delay between msg:METADATA_UPDATED
(triggered by faulty) and msg:REMOVE was sufficient for node2 to
reload the disk info (written by node1).
After a1fd37f97808, node1 no longer waits between faulty and remove,
causing it to send msg:REMOVE while node2 is still reloading disk info.
This often results in node2 failing to remove the faulty disk.

== how to trigger ==

set up a 2-node cluster (node1 & node2) with disks vdc & vdd.

on node1:
mdadm -CR /dev/md0 -l1 -b clustered -n2 /dev/vdc /dev/vdd --assume-clean
ssh node2-ip mdadm -A /dev/md0 /dev/vdc /dev/vdd
mdadm --manage /dev/md0 --fail /dev/vdc --remove /dev/vdc

check array status on both nodes with "mdadm -D /dev/md0".
node1 output:
    Number   Major   Minor   RaidDevice State
       -       0        0        0      removed
       1     254       48        1      active sync   /dev/vdd
node2 output:
    Number   Major   Minor   RaidDevice State
       -       0        0        0      removed
       1     254       48        1      active sync   /dev/vdd

       0     254       32        -      faulty   /dev/vdc

Fixes: a1fd37f97808 ("md: Don't wait for MD_RECOVERY_NEEDED for HOT_REMOVE_DISK ioctl")
Signed-off-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Su Yue <glass.su@suse.com>
Link: https://lore.kernel.org/linux-raid/20250728042145.9989-1-heming.zhao@suse.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>