Make Pages disk access fail in web server

Previously, when `GITLAB_PAGES_DENY_DISK_ACCESS` was set, accessing
`Gitlab::Pages::Settings.path` from a web process would track an
exception and continue on.

Now it will simply raise the exception and fail. This is to make it
easier for developers to find a problem with their code before taking it
to production on GitLab.com, where the Pages NFS mount will soon be
removed.

lib/gitlab/pages/settings.rb

@@ -7,11 +7,7 @@ module Gitlab
 
       def path
         if ::Gitlab::Runtime.web_server? && ENV['GITLAB_PAGES_DENY_DISK_ACCESS'] == '1'
-          begin
-            raise DiskAccessDenied
-          rescue DiskAccessDenied => ex
-            ::Gitlab::ErrorTracking.track_exception(ex)
-          end
+          raise DiskAccessDenied
         end
 
         super

spec/lib/gitlab/pages/settings_spec.rb

@@ -10,12 +10,6 @@ RSpec.describe Gitlab::Pages::Settings do
 
     it { is_expected.to eq('the path') }
 
-    it 'does not track calls' do
-      expect(::Gitlab::ErrorTracking).not_to receive(:track_exception)
-
-      subject
-    end
-
     context 'when running under a web server' do
       before do
         allow(::Gitlab::Runtime).to receive(:web_server?).and_return(true)
@@ -23,24 +17,13 @@ RSpec.describe Gitlab::Pages::Settings do
 
       it { is_expected.to eq('the path') }
 
-      it 'does not track calls' do
-        expect(::Gitlab::ErrorTracking).not_to receive(:track_exception)
-
-        subject
-      end
-
       context 'with the env var' do
         before do
           stub_env('GITLAB_PAGES_DENY_DISK_ACCESS', '1')
         end
 
-        it { is_expected.to eq('the path') }
-
-        it 'tracks a DiskAccessDenied exception' do
-          expect(::Gitlab::ErrorTracking).to receive(:track_exception)
-            .with(instance_of(described_class::DiskAccessDenied)).and_call_original
-
-          subject
+        it 'raises a DiskAccessDenied exception' do
+          expect { subject }.to raise_error(described_class::DiskAccessDenied)
         end
       end
     end