Remove FF ci_project_git_depth

Remove redundant FF

app/presenters/ci/build_runner_presenter.rb

@@ -27,7 +27,7 @@ module Ci
     def git_depth
       if git_depth_variable
         git_depth_variable[:value]
-      elsif Feature.enabled?(:ci_project_git_depth, default_enabled: true)
+      else
         project.ci_default_git_depth
       end.to_i
     end

spec/presenters/ci/build_runner_presenter_spec.rb

@@ -138,16 +138,6 @@ describe Ci::BuildRunnerPresenter do
     it 'defaults to git depth setting for the project' do
       expect(git_depth).to eq(build.project.ci_default_git_depth)
     end
-
-    context 'when feature flag :ci_project_git_depth is disabled' do
-      before do
-        stub_feature_flags(ci_project_git_depth: { enabled: false })
-      end
-
-      it 'defaults to 0' do
-        expect(git_depth).to eq(0)
-      end
-    end
   end
 
   describe '#refspecs' do