Remove the failing tests for deprecated RPCs

It's an overkill to test the internal logic of the Gitaly
It's enough to test that a particular RPC has been called (it's tested)

The deprecated RPCs are going to be removed soon, so let's just remove
the tests

spec/support/shared_examples/workers/concerns/git_garbage_collect_methods_shared_examples.rb

@@ -230,76 +230,6 @@ RSpec.shared_examples 'can collect git garbage' do |update_statistics: true|
         stub_feature_flags(optimized_housekeeping: false)
       end
 
-      it 'incremental repack adds a new packfile' do
-        create_objects(resource)
-        before_packs = packs(resource)
-
-        expect(before_packs.count).to be >= 1
-
-        subject.perform(resource.id, 'incremental_repack', lease_key, lease_uuid)
-        after_packs = packs(resource)
-
-        # Exactly one new pack should have been created
-        expect(after_packs.count).to eq(before_packs.count + 1)
-
-        # Previously existing packs are still around
-        expect(before_packs & after_packs).to eq(before_packs)
-      end
-
-      it 'full repack consolidates into 1 packfile' do
-        create_objects(resource)
-        subject.perform(resource.id, 'incremental_repack', lease_key, lease_uuid)
-        before_packs = packs(resource)
-
-        expect(before_packs.count).to be >= 2
-
-        subject.perform(resource.id, 'full_repack', lease_key, lease_uuid)
-        after_packs = packs(resource)
-
-        expect(after_packs.count).to eq(1)
-
-        # Previously existing packs should be gone now
-        expect(after_packs - before_packs).to eq(after_packs)
-
-        expect(File.exist?(bitmap_path(after_packs.first))).to eq(bitmaps_enabled)
-      end
-
-      it 'gc consolidates into 1 packfile and updates packed-refs' do
-        create_objects(resource)
-        before_packs = packs(resource)
-        before_packed_refs = packed_refs(resource)
-
-        expect(before_packs.count).to be >= 1
-
-        # It's quite difficult to use `expect_next_instance_of` in this place
-        # because the RepositoryService is instantiated several times to do
-        # some repository calls like `exists?`, `create_repository`, ... .
-        # Therefore, since we're instantiating the object several times,
-        # RSpec has troubles figuring out which instance is the next and which
-        # one we want to mock.
-        # Besides, at this point, we actually want to perform the call to Gitaly,
-        # otherwise we would just use `instance_double` like in other parts of the
-        # spec file.
-        expect_any_instance_of(Gitlab::GitalyClient::RepositoryService) # rubocop:disable RSpec/AnyInstanceOf
-          .to receive(:garbage_collect)
-          .with(bitmaps_enabled, prune: false)
-          .and_call_original
-
-        subject.perform(resource.id, 'gc', lease_key, lease_uuid)
-        after_packed_refs = packed_refs(resource)
-        after_packs = packs(resource)
-
-        expect(after_packs.count).to eq(1)
-
-        # Previously existing packs should be gone now
-        expect(after_packs - before_packs).to eq(after_packs)
-
-        # The packed-refs file should have been updated during 'git gc'
-        expect(before_packed_refs).not_to eq(after_packed_refs)
-
-        expect(File.exist?(bitmap_path(after_packs.first))).to eq(bitmaps_enabled)
-      end
-
       it 'cleans up repository after finishing' do
         expect(resource).to receive(:cleanup).and_call_original