Re-enable browser tests on enwiki for search-specialpages.feature

Now that the code to satisfy the tests is on enwiki, let's make sure
we're actually running browser tests against it.

Change-Id: If4e9f21faed20d4bcbe4e07114149f9d852a8b1a
Merge "Re-enable browser tests on enwiki for search-specialpages.feature"