Fix missing gpg and deprecated apt-key for elasticsearch. #438

[vjrj]

Installing the image-service playbook alone in a VM I get:

TASK [ansible-elasticsearch : Debian - Add Elasticsearch repository key] *******
Tuesday 06 October 2020  16:45:48 +0200 (0:00:01.709)       0:00:47.266 ******* 
fatal: [ala-install-test-2]: FAILED! => {"changed": false, "msg": "Failed to find required executable gpg in paths: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin"}

so I patched following #430 (comment) and #438 and the image-service playbook worked.

I used a plain .asc file instead of a keyring that probably required also the gpg package.

[ansell]

Verified that it doesn't break the image-service playbook.