[webstatscollector] Adjust 'wiki' path check

Webstatscollector tokenizes at '/' and checks that 'wiki' is the first
of the path tokens. So, the path has to start in '/wiki', not only
contain 'wiki'.

Change-Id: I09c9a07e32d804d5983938929df1e1463d22d9bb
[webstatscollector] Add 'CentralAutoLogin' condition

As of webstatscollector's commit
  0d7af935f989d5c539a4d2febde93ea0ae62571b
, it no longer counts requests to 'wiki/Special:CentralAutoLogin/'.

Change-Id: If6c0b2bec423de805e53fe37f43b293d18e0e752
[webstatscollector] Add '[uU]ndefined' condition

Requests to 'undefined' and 'Undefined' get excluded as they seem to
stem from JavaScript glitches for the by far bigger part.

Bug: 66352
Change-Id: I4fd0d15e1e5ae50a6b51c0e58821f1edc98d3ed8
[webstatscollector] Add condition to not count redirects

Those codes are just redirects. Browsers will request the desired
document in a separate request.

Bug: 71790
Change-Id: I60bf810afdd92ecde245fbe08ddf1ec8b145a8af