7335 FIX Fixed broken regex based hostname translation in EC

7335 FIX Fixed broken regex based hostname translation in EC

The hostname translation of the EC was broken since release of
Check_MK 1.4.0 (caused by #3687). This issue lead to dropped events
once the translation has been condifgured. The problem was visible
in the mkeventd.log in the following form:

C+:
 2019-04-04 11:36:24,286 [40] [cmk.mkeventd.EventServer] Unable to parse host "HOST" ('tuple' object has no attribute 'endswith')
Traceback (most recent call last):
  File "/omd/sites/snmp/lib/python/cmk/ec/main.py", line 2787, in do_translate_hostname
    event["host"] = self.translate_hostname(event["host"])
  File "/omd/sites/snmp/lib/python/cmk/ec/main.py", line 2768, in translate_hostname
    if not regex.endswith('$'):
AttributeError: 'tuple' object has no attribute 'endswith'
C-:

Change-Id: I5d8b8dee696c02ac29d8118e66104338b91fbdea