fix: fishing zombie throwing rod while dead

[leumasme]

Closes GTNewHorizons/GT-New-Horizons-Modpack#17058

EntityFishingZombie uses a different implementation (using onLivingUpdate) for the fishing hook logic than EntityFishingPigZombie and EntityFishingSilverfish.
This is necessary because the base Zombie uses the modern AI Task System, where attackEntity isn't used anymore.
An oversight was made however: attackEntity doesn't get called if the Entity is dead, but onLivingUpdate does.
This causes Fishing Zombies to be able to throw Fishing Rods while dead (in the Dying animation before the entity is deleted).

0031856.mp4

(Note the fishing rod bobber being being thrown after the Zombie is killed. This can still hit and pull players)

Just adding a check with isMovementBlocked fixes this (using this function instead of isDead seems to be convention for stopping Mob AI).