performance.wikimedia.org: use ScriptAlias rather than ScriptAliasMatch

reporter.py is the only valid entry-point, so using a ScriptAliasMatch with a
regex that can be used to execute any .py file in /srv/deployment/reporter is
insecure. So use ScriptAlias instead which points specifically to reporter.py
and nothing else.

Change-Id: I88162c1e6f8ee5bc151c096e850180ce4a1f15bd