aplinfo: see trusted keys as build product, always assembly

aplinfo: see trusted keys as build product, always assembly

Don't track the binary trustedkeys.gpg but see it just as normal
build product with the armored keys as source.

This ensures we always ship those from TRUSTED_KEYS variable, not
more, not less.

Instead of the "gpg import+export in temporary home dir" just
de-armor and concatenate them our self, that's what happens anyway.

This could be even simplified by just using base64 -d on the pubkeys,
after the non base64 stuff was trimmed, that would omit our need for
gpg here completely.

Thanks to Wolfgang B. for giving the idea to just do simple stuff :)

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>