Do not backoff hook if it is permanently disabled

https://gitlab.com/gitlab-org/gitlab/-/merge_requests/75175/diffs#note_770971141

app/models/hooks/web_hook.rb

@@ -92,7 +92,7 @@ class WebHook < ApplicationRecord
   end
 
   def backoff!
-    return if backoff_count >= MAX_FAILURES && temporarily_disabled?
+    return if permanently_disabled? || (backoff_count >= MAX_FAILURES && temporarily_disabled?)
 
     assign_attributes(disabled_until: next_backoff.from_now, backoff_count: backoff_count.succ.clamp(0, MAX_FAILURES))
     save(validate: false)

spec/models/hooks/web_hook_spec.rb

@@ -330,6 +330,20 @@ RSpec.describe WebHook do
       expect { hook.backoff! }.to change(hook, :backoff_count).by(1)
     end
 
+    context 'when the hook is permanently disabled' do
+      before do
+        allow(hook).to receive(:permanently_disabled?).and_return(true)
+      end
+
+      it 'does not set disabled_until' do
+        expect { hook.backoff! }.not_to change(hook, :disabled_until)
+      end
+
+      it 'does not increment the backoff count' do
+        expect { hook.backoff! }.not_to change(hook, :backoff_count)
+      end
+    end
+
     context 'when we have backed off MAX_FAILURES times' do
       before do
         stub_const("#{described_class}::MAX_FAILURES", 5)