Arc - BeanManager#getEvent should be adding @Default qualifier

[manovotn]

Currently we are not adding @Default qualifier to events fired via BM#getEvent() when there is no other explicit qualifier. This seems to be against specification although there are no explicit TCKs asserting this. While this is somewhat grey area that we should revisit and clarify for the next spec version, we can definitely perform some improvements even now.
Ideally we want this behavior to be close to what BM#getInstance does WRT default qualifier.

Note that an event fired via @Inject Event<X> will have @Default added as expected.

For future reference, Weld behaves exactly the same and we are fixing that via https://issues.redhat.com/browse/WELD-2775

[quarkus-bot]

/cc @Ladicek (arc), @mkouba (arc)