mgr/dashboard: fix rbd form mirroring toggle

mgr/dashboard: fix rbd form mirroring toggle

- fix the toggle not working while editing the image
- the rbd form mirroring toggle doesn't disable/enable the mirror mode
when you change the pool.

- also re-arrange the form in a way that the required fields are together.
- disable mirroring when selecting the namespace

Resolves: rhbz#2403464

Fixes: https://tracker.ceph.com/issues/72458
Signed-off-by: Nizamudeen A <nia@redhat.com>
(cherry picked from commit 1efd37d4b5fc4363c6c86a84ede9c826c94d2c22)
(cherry picked from commit 63e7555a1f3d877faf54047a46e6499ed2cc05e3)