[patch] MaaS: mcp.rsa.pub to auth keys via pillar

[patch] MaaS: mcp.rsa.pub to auth keys via pillar

Drop one questionable patch responsible for MaaS node authorized
keys to include mcp.rsa.pub by reading the contents of authorized
keys on mas01, assuming mcp.rsa.pub will be on the first line.

Instead, export the contents of the public key using a shell env
var during deploy, which gets expanded via maas_pdf j2 template
into a reclass param, leveraging existing salt-formula-maas sshprefs
mechanism for delivering the key to MaaS.

Since we require the public key to exist before expanding templates,
move `generate_ssh_key` call outside the current infrastructure
handling block, allowing it to execute during all `deploy.sh` calls,
even for dry-runs.

Change-Id: I0f53b0f764a2fafd292e0ffd399c284acf61bd30
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>