Remove noparent from OWNERS

The noparent setting is interfering with how the code-owners plugin
manages OWNERS permissions (preventing refs/meta/config OWNERS from
being applied). Since there's no valid OWNERS file in the parent
directories for this repository, there's also no need to maintain the
noparent directive.

Bug: 206135094
Tag: #floss
Test: N/A
Change-Id: Ic00788c4894ad98dc2d5a34289608b68f84feae8