php_xdebug_cli_enable is unused

[danepowell]

This is a follow up to geerlingguy/ansible-role-php-xdebug#47

As indicated in that issue, php_xdebug_cli_enable is no longer used and references to it should be removed.

However, it's being replaced by a new option php_xdebug_cli_disable in geerlingguy/ansible-role-php-xdebug#54. So it might make sense to just switch one for the other.

[geerlingguy]

Thanks!

[PieterDC]

Thanks for your contributions.
I just wanted to note that (looking at 7c3d210) it seems the default changed from enabled by default to disabled by default.