NumberInput Undo this [issue](https://github.com/patternfly/patternfly-react/issues/8462) / [pr](https://github.com/patternfly/patternfly-react/pull/8502). AC: - allowing the empty input is the default behavior - the allowEmptyInput prop is removed - tests/examples are updated (remove allowEmptyInput) and working
