apt_key: fix key lookup for 64 bit key ids

Fixes #7018 by extending `all_keys` to work with either short or long keys.

Also removes the ununsed method `key_present`.
Merge branch 'apt_key_format' of https://github.com/andreasf/ansible into andreasf-apt_key_format
Merge branch 'andreasf-apt_key_format' into devel