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

Previously, calling `$interval.cancel()` with a promise that was not
generated by a call to `$interval()` 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
`$interval.cancel()`.
With this commit, `$interval.cancel()` will throw an error if called
with a non-$interval promise, thus surfacing errors that would otherwise
go unnoticed.

Related to #16424.

BREAKING CHNAGE:

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

Before:
```js
var promise = $interval(doSomething, 1000, 5).then(doSomethingElse);
$interval.cancel(promise);  // No error; interval NOT canceled.
```

After:
```js
var promise = $interval(doSomething, 1000, 5).then(doSomethingElse);
$interval.cancel(promise);  // Throws error.
```

Correct usage:
```js
var promise = $interval(doSomething, 1000, 5);
var newPromise = promise.then(doSomethingElse);
$interval.cancel(promise);  // Interval canceled.
```

Closes #16476