MDL-48107 tool_monitor: added total subs to the delete rule string

Also made some minor language string changes.
MDL-48107 tool_monitor: prevent site rule removal when deleting a course
MDL-48107 tool_monitor: extended automated tests

Also adjusted them so they will pass with these changes.
Merge branch 'MDL-48107_master' of https://github.com/markn86/moodle
Automatically generated installer lang files
Merge branch 'install_master' of https://git.in.moodle.com/amosbot/moodle-install
Moodle release 2.8
weekly back-to-dev release 2.9dev