fix($timeout): throw when trying to cancel non-$timeout promise

Previously, calling `$timeout.cancel()` with a promise that was not
generated by a call to `$timeout()` would do nothing. This could, for
example, happen when calling `.then()`/`.catch()` on the returned
promise, which creates a new promise, and passing that to
`$timeout.cancel()`.
With this commit, `$timeout.cancel()` will throw an error if called with
a non-$timeout promise, thus surfacing errors that would otherwise go
unnoticed.

Fixes #16424

BREAKING CHNAGE:

`$timeout.cancel()` will throw an error if called with a promise that
was not generated by `$timeout()`. Previously, it would silently do
nothing.

Before:
```js
var promise = $timeout(doSomething, 1000).then(doSomethingElse);
$timeout.cancel(promise);  // No error; timeout NOT canceled.
```

After:
```js
var promise = $timeout(doSomething, 1000).then(doSomethingElse);
$timeout.cancel(promise);  // Throws error.
```

Correct usage:
```js
var promise = $timeout(doSomething, 1000);
var newPromise = promise.then(doSomethingElse);
$timeout.cancel(promise);  // Timeout canceled.
```