Remove skipped examples in filtered issues feature spec

We perform a ton of expensive setup in this spec, via both `before` and
`let!`. When we use `skip` inside an `it` block, rather than skipping
the block entirely via `xit`, we still perform this expensive setup,
only to do absolutely nothing with it, resulting in wasted time.
Minutes, in this case.

Further, these specs have been sitting in our test suite for about seven
months now, so the likelihood of them being addressed soon seems low.

spec/features/issues/filtered_search/filter_issues_spec.rb

@@ -103,14 +103,6 @@ describe 'Filter issues', js: true do
         expect_issues_list_count(5)
         expect_filtered_search_input_empty
       end
-
-      it 'filters issues by invalid author' do
-        skip('to be tested, issue #26546')
-      end
-
-      it 'filters issues by multiple authors' do
-        skip('to be tested, issue #26546')
-      end
     end
 
     context 'author with other filters' do
@@ -165,10 +157,6 @@ describe 'Filter issues', js: true do
         expect_filtered_search_input(search_term)
       end
     end
-
-    it 'sorting' do
-      skip('to be tested, issue #26546')
-    end
   end
 
   describe 'filter issues by assignee' do
@@ -190,14 +178,6 @@ describe 'Filter issues', js: true do
         expect_issues_list_count(8, 1)
         expect_filtered_search_input_empty
       end
-
-      it 'filters issues by invalid assignee' do
-        skip('to be tested, issue #26546')
-      end
-
-      it 'filters issues by multiple assignees' do
-        skip('to be tested, issue #26546')
-      end
     end
 
     context 'assignee with other filters' do
@@ -250,12 +230,6 @@ describe 'Filter issues', js: true do
         expect_filtered_search_input(search_term)
       end
     end
-
-    context 'sorting' do
-      it 'sorts' do
-        skip('to be tested, issue #26546')
-      end
-    end
   end
 
   describe 'filter issues by label' do
@@ -278,10 +252,6 @@ describe 'Filter issues', js: true do
         expect_filtered_search_input_empty
       end
 
-      it 'filters issues by invalid label' do
-        skip('to be tested, issue #26546')
-      end
-
       it 'filters issues by multiple labels' do
         input_filtered_search("label:~#{bug_label.title} label:~#{caps_sensitive_label.title}")
 
@@ -493,12 +463,6 @@ describe 'Filter issues', js: true do
         expect_filtered_search_input_empty
       end
     end
-
-    context 'sorting' do
-      it 'sorts' do
-        skip('to be tested, issue #26546')
-      end
-    end
   end
 
   describe 'filter issues by milestone' do
@@ -535,14 +499,6 @@ describe 'Filter issues', js: true do
         expect_filtered_search_input_empty
       end
 
-      it 'filters issues by invalid milestones' do
-        skip('to be tested, issue #26546')
-      end
-
-      it 'filters issues by multiple milestones' do
-        skip('to be tested, issue #26546')
-      end
-
       it 'filters issues by milestone containing special characters' do
         special_milestone = create(:milestone, title: '!@\#{$%^&*()}', project: project)
         create(:issue, title: "Issue with special character milestone", project: project, milestone: special_milestone)
@@ -618,12 +574,6 @@ describe 'Filter issues', js: true do
         expect_filtered_search_input(search_term)
       end
     end
-
-    context 'sorting' do
-      it 'sorts' do
-        skip('to be tested, issue #26546')
-      end
-    end
   end
 
   describe 'filter issues by text' do