Fix 2D editor stuck in dragging state

[timothyqiu]

To reproduce the problem, try dragging a child control of a container in the 2D editor.

Only reproducible on master, not in dev2.

[kleonc]

It does fix being stuck in the drag state, but now it spam warns toast notifications. 🤔

cc @YeldhamDev as this is likely related to #111456.

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• v4.5.1.stable.official [f62fdbd], enters drag state (at least indicates so by the cursor), single warning per drag:

Godot_v4.5.1-stable_win64_V0s1xHb8N1.mp4

• master (0870525), stuck in drag, single warning:

godot.windows.editor.dev.x86_64_5wmwX96NHY.mp4

• this PR, doesn't enter drag state (at least the cursor doesn't change), spam toast-warnings:

godot.windows.editor.dev.x86_64_BDho6DZJ1l.mp4

[akien-mga]

Superseded by #112249.