Previously searching for posters would use full name or username depending on the `[ui].DEFAULT_SHOW_FULL_NAME` setting, now it searches for both of them regardless of the setting.
This also a fixes a bug when `[ui].DEFAULT_SHOW_FULL_NAME=true` that users without a full name where not able to searched for.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/10394
Reviewed-by: Beowulf <beowulf@beocode.eu>
Co-authored-by: BtbN <btbn@btbn.de>
Co-committed-by: BtbN <btbn@btbn.de>