Fix OWNERS for SpaLib

SettingsLib's xml files does not need owners approval, but SpaLib's xml
files will be protected by owners approval.

Set "per-file *.xml = set noparent" will also remove all owners, which
means no owners can approve.

So move the "set noparent" to the SpaLib level to fix.

Bug: 235727273
Test: n/a
Change-Id: I2c20c788688698afec63001f3af3693568bae034