CI: Factorize ansible-playbook flags (#11173)

We have inconsistent sets of options passed to the playbooks during our
CI runs.

Don't run ansible-playbook directly, instead factorize the execution in
a bash function using all the common flags.
Also remove various ENABLE_* variables and instead directly test for the
relevant conditions at execution time, as this makes it more obvious and
does not force one to go back and forth in the script.