when browser_archiving_disabled_enforce=1 the Auto archiver will not process the VisitFrequency reports

[mattab]

There is a bug in piwik where if browser_archiving_disabled_enforce=1 in the config, the VisitFrequency reports are not processed.

[mattab]

In 3201579: Fixes #4857 - When trigger=archivephp is found in the request, never disable archiving.
this will make sure that visitFrequency, when calling VisitsSummary.get with a segment=visitorType==returning, then it will be pre-processed at all times by archive.php.

[mattab]

see also #2981

[mattab]

In c1f375e: Fixes #4857