profiles: Unmask app-metrics/{alertmanager,prometheus,*_exporter}
Mask was applied because of "incorrect license information" in commit
431fad963f6677e8f58276b1433f9b9f56e75ca9. While you could list _more_
licenses, and people started to work on this now, these packages are all
licensed under Apache 2.0 which explicitly lists BSD, MIT.. as authorized
3rd party licenses. Therefore a mask due to incorrect licenses isn't
justified.
Bug: https://bugs.gentoo.org/695212
Signed-off-by: Thomas Deutschmann <whissi@gentoo.org>