provisioners/ansible: spare machine.ssh_info calls

As a result of #4670 and the safe decision to not memoize
machine.ssh_info (see 89a4a29d65cace4d970d0f220ad01815883ab8aa and
5036d16461cfafde5274836d51b97740c23bd4eb), it is preferable to store the
ssh_info hashes and avoid multiple function calls when generating the
ansible inventory.
core: fully revert stuff from ssh_info memoization

5036d16461cfafde5274836d51b97740c23bd4eb only partially reverted
89a4a29d65cace4d970d0f220ad01815883ab8aa.

Related to #4670.