fix(creation): honor suspend_mobject_updating in Create/Uncreate

[Chessing234]

Changelog / Overview

Create/Uncreate ignored suspend_mobject_updating: updaters on the target kept running during the animation.

Cause

ShowPartial rebuilds the mobject every frame from starting_mobject via pointwise_become_partial. Animation.begin() only suspends self.mobject, so the reference copy's updaters kept firing (it is in get_all_mobjects_to_update) and their drift was copied back into the result each frame — making the flag a no-op.

Fix

When suspend_mobject_updating is set, also suspend starting_mobject in ShowPartial.begin().

Testing

def upd(m, dt): m.shift(RIGHT*dt)
d1 = Dot().add_updater(upd); d2 = Dot().add_updater(upd)
self.play(Create(d1, suspend_mobject_updating=True),
          Create(d2, suspend_mobject_updating=False), run_time=2)
# before: d1.x == d2.x == 1.93 (both drift)
# after:  d1.x == 0.0, d2.x == 1.93

Existing tests/module/animation/test_creation.py pass.

Fixes #4763

Made with Cursor

[Chessing234]

Superseded by rebased #4879 (old branch had diverged from main).