fix: disable promise callback when {#await} is destroyed

[adiguba]

The promise callbacks used on {#await} can resolve after the block has been destroyed, which leads to other errors.

See #13236

A simple solution : set the input to null in order to disable the callbacks.

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[trueadm]

Please could you add a test case for this?

[paoloricciuti]

P.s. if you need it here's a super minimal reproduction...if you use this in the test you can just check the checkbox, uncheck it and assert that the logs is an empty array (make sure to wait the time of the resolution...to be very sure you can even expose the promise itself to be able to await it in the test)

[adiguba]

I added a test under runtime-runes/samples/await-pending-destroy

Not sur if it's the good place. I tried to make it as simple as possible...

[paoloricciuti]

Ugh I forgot to add a change set before merging, silly me

[adiguba]

This should close the #13236