Remove parent.start() from CancellableContinuationImpl.kt

[qwwdfsad]

It seems to be the legacy from times when CC was a Job, in order to observe behaviour change, a specific example should be accurately made.

Note that this changes the behaviour of the following (weird, but still) test:

@Test
fun suspendCancellableContinuationParentStart() = runTest {
    val job = launch(start = CoroutineStart.LAZY) { println("Aha!") }
    ::suspendCancellable.startCoroutine(Continuation(job) {})
}

suspend fun suspendCancellable() = suspendCancellableCoroutine<Int> { 
    it.resumeWith(Result.success(42))
}

[elizarov]

💯 Great catch