Fix completeExceptionally() wrapping in AndroidFuture.

writeToParcel() called get(), which obtained the exception wrapped in ExecutionException.
ExecutionException is not handled by Parcel's exception parcelling mechanism, causing it
to throw out of completeExceptionally without sending any data, leading to hangs.

Bug: 145838772
Test: presubmit
Change-Id: I5bb9b8b441264195039c9a2abe6a617af4ec8316