GamepadManager: Fixed issue where providing scene object to constructor would prevent status updates

[PolygonalSun]

A user on the forum found an issue where the GamepadManager wouldn't update its gamepad statuses when this._scene was defined. The fix was to remove these checks. Thanks to user CiderPunk for finding this issue.

Forum Link: https://forum.babylonjs.com/t/gamepad-events-not-triggering/40362

[bjsplat]

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[bjsplat]

Snapshot stored with reference name:
refs/pull/13798/merge

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[RaananW]

What was the reasoning behind checking if the scene existed?