Remove `:quarantine` from most of the quarantined spec examples

As can be seen in the following jobs, it seems we only have one true broken test in quarantine right now, and only a few flaky tests (that pass after retries):

• https://gitlab.com/gitlab-org/gitlab/-/jobs/354760202
• https://gitlab.com/gitlab-org/gitlab/-/jobs/354765294
• https://gitlab.com/gitlab-org/gitlab/-/jobs/354769952
• https://gitlab.com/gitlab-org/gitlab/-/jobs/354798151
• https://gitlab.com/gitlab-org/gitlab/-/jobs/354817965
• https://gitlab.com/gitlab-org/gitlab/-/jobs/354823560
• https://gitlab.com/gitlab-org/gitlab/-/jobs/355040857

1647 Search bar
1648   clear search button
1649 1st Try error in ./spec/features/issues/filtered_search/search_bar_spec.rb:91:
1650 expected to find visible css ".filter-dropdown .filter-dropdown-item" within #<Capybara::Node::Element tag="div" path="/HTML/BODY[1]/DIV[1]/DIV[2]/DIV[3]/DIV[1]/DIV[3]/DIV[1]/DIV[1]/FORM[1]/DIV[2]/DIV[1]/DIV[2]/DIV[2]"> 6 times, found 8 matches: "author\n:@author", "assignee\n:@assignee", "milestone\n:%milestone", "release\n:tag name", "label\n:~label", "my-reaction\n:emoji", "weight\n:number", "confidential\n:Yes or No"
1651 RSpec::Retry: 2nd try ./spec/features/issues/filtered_search/search_bar_spec.rb:91
1652 2nd Try error in ./spec/features/issues/filtered_search/search_bar_spec.rb:91:
1653 expected to find visible css ".filter-dropdown .filter-dropdown-item" within #<Capybara::Node::Element tag="div" path="/HTML/BODY[1]/DIV[1]/DIV[2]/DIV[3]/DIV[1]/DIV[3]/DIV[1]/DIV[1]/FORM[1]/DIV[2]/DIV[1]/DIV[2]/DIV[2]"> 6 times, found 8 matches: "author\n:@author", "assignee\n:@assignee", "milestone\n:%milestone", "release\n:tag name", "label\n:~label", "my-reaction\n:emoji", "weight\n:number", "confidential\n:Yes or No"
1654 RSpec::Retry: 3rd try ./spec/features/issues/filtered_search/search_bar_spec.rb:91
1655 3rd Try error in ./spec/features/issues/filtered_search/search_bar_spec.rb:91:
1656 expected to find visible css ".filter-dropdown .filter-dropdown-item" within #<Capybara::Node::Element tag="div" path="/HTML/BODY[1]/DIV[1]/DIV[2]/DIV[3]/DIV[1]/DIV[3]/DIV[1]/DIV[1]/FORM[1]/DIV[2]/DIV[1]/DIV[2]/DIV[2]"> 6 times, found 8 matches: "author\n:@author", "assignee\n:@assignee", "milestone\n:%milestone", "release\n:tag name", "label\n:~label", "my-reaction\n:emoji", "weight\n:number", "confidential\n:Yes or No"
1657 RSpec::Retry: 4th try ./spec/features/issues/filtered_search/search_bar_spec.rb:91
1658     resets the dropdown filters (FAILED - 1)
1659   HTML screenshot: /builds/gitlab-org/gitlab/tmp/capybara/screenshot_2019-11-19-14-50-10.930.html
1660   Image screenshot: /builds/gitlab-org/gitlab/tmp/capybara/screenshot_2019-11-19-14-50-10.930.png

1957 Finished in 14 minutes 0 seconds (files took 3 minutes 42.3 seconds to load)
1958 69 examples, 1 failure
1959 Failed examples:
1960 rspec ./spec/features/issues/filtered_search/search_bar_spec.rb:91 # Search bar clear search button resets the dropdown filters

That means we should try to remove :quarantine from the most stable tests.