allow_low_quality_matches is always set to True

**Describe the bug**
`allow_low_quality_matches` in `set_regular_matcher` is always set to `True` and it's not using value from the argument, in retinanet.
https://github.com/Project-MONAI/MONAI/blob/e9f48e3416a506c0775fbe2366528ff1a30906bc/monai/apps/detection/networks/retinanet_detector.py#L327
