Disallow Pages NFS access in web server

Previously this was controlled by the `GITLAB_PAGES_DENY_DISK_ACCESS`
environment variable. As we have been running with that variable enabled
on GitLab.com with no issues for a while now, we can remove this check
entirely.

lib/gitlab/pages/settings.rb

@@ -6,7 +6,7 @@ module Gitlab
       DiskAccessDenied = Class.new(StandardError)
 
       def path
-        if ::Gitlab::Runtime.web_server? && ENV['GITLAB_PAGES_DENY_DISK_ACCESS'] == '1'
+        if ::Gitlab::Runtime.web_server? && !::Gitlab::Runtime.test_suite?
           raise DiskAccessDenied
         end
 

spec/lib/gitlab/pages/settings_spec.rb

@@ -10,21 +10,14 @@ RSpec.describe Gitlab::Pages::Settings do
 
     it { is_expected.to eq('the path') }
 
-    context 'when running under a web server' do
+    context 'when running under a web server outside of test mode' do
       before do
+        allow(::Gitlab::Runtime).to receive(:test_suite?).and_return(false)
         allow(::Gitlab::Runtime).to receive(:web_server?).and_return(true)
       end
 
-      it { is_expected.to eq('the path') }
-
-      context 'with the env var' do
-        before do
-          stub_env('GITLAB_PAGES_DENY_DISK_ACCESS', '1')
-        end
-
-        it 'raises a DiskAccessDenied exception' do
-          expect { subject }.to raise_error(described_class::DiskAccessDenied)
-        end
+      it 'raises a DiskAccessDenied exception' do
+        expect { subject }.to raise_error(described_class::DiskAccessDenied)
       end
     end
   end