Stop using removed WikiPage::factory

[JeroenDeDauw]

For

• [Filtered] Fix call to undefined method WikiPage::factory #962

Untested

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.22%. Comparing base (ca6b858) to head (d9a0513).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
formats/filtered/src/View/MapView.php	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #963      +/-   ##
============================================
- Coverage     46.23%   46.22%   -0.02%     
  Complexity     2361     2361              
============================================
  Files            80       80              
  Lines          9158     9160       +2     
============================================
  Hits           4234     4234              
- Misses         4924     4926       +2     

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[malberts]

Tested that the page no longer throws an exception.