MEDIUM: mworker: wait mode use standard init code path

MEDIUM: mworker: wait mode use standard init code path

The mworker waitpid mode (which is used when a reload failed to apply
the new configuration) was still using a specific initialisation path.
That's a problem since we use a polling loop in the master now, the
master proxy is not initialized and the master CLI is not activated.

This patch removes the initialisation code of the wait mode and
introduce the MODE_MWORKER_WAIT in order to use the same init path as
the MODE_MWORKER with some exceptions. It allows to use the master proxy
and the master CLI during the waitpid mode.