Automatic merge from submit-queue (batch tested with PRs 46149, 45897, 46293, 46296, 46194)

check flag format in file known-flags.txt

All flags in file hack/verify-flags/known-flags.txt should contain
character -, this change check it to prevent adding useless flags
to known-flags.txt
ref #45948 

**Release note**:

```
NONE
```