Potential memory leak.

During reviewing of code base I found that:
https://github.com/smithy-lang/smithy-typescript/blob/main/packages/util-waiter/src/createWaiter.ts#L12
Adds event listener but do not remove it.
From my point of view this could lead to memory leak.
In my case I have long running operation with single abort signal for it.
And it looks like a problem. 