The bug:
The warden can get pushed around when emerging and digging.

Steps to reproduce:

• Activate some sculk shriekers
• Once warden starts emerging, try pushing it around by running into its hitbox.
• kill the warden with /kill @e[type=warden]
• Summon a new warden that will start digging right away
• /summon minecraft:warden ~ ~ ~ {Health:1b}

  (The Warden currently digs down right away if assigned any nbt data as can be seen in MC-249393)

• Try pushing it around by running into its hitbox while it is digging.

Observed results:
The Warden can be pushed around when emerging and digging.

Expected result:
The Warden won't have any collision until it's fully emerged or once it has started digging.