Revert "nagios_common: Add compat checkcommand definition temporarily"

Puppet seems to have run everywhere necessary, and a
manual check reveals that nobody is using the old
name anymore.

This reverts commit 71c83329f323bb1de18b52e40d794667d02b4818.

Change-Id: I8d9d88743da78b2747ebbd160dc4daebd97881f4