Switch from using SharedState to Cache for mergeability cache

MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/76755

lib/gitlab/merge_requests/mergeability/redis_interface.rb

@@ -7,13 +7,13 @@ module Gitlab
         VERSION = 1
 
         def save_check(merge_check:, result_hash:)
-          Gitlab::Redis::SharedState.with do |redis|
+          Gitlab::Redis::Cache.with do |redis|
             redis.set(merge_check.cache_key + ":#{VERSION}", result_hash.to_json, ex: EXPIRATION)
           end
         end
 
         def retrieve_check(merge_check:)
-          Gitlab::Redis::SharedState.with do |redis|
+          Gitlab::Redis::Cache.with do |redis|
             Gitlab::Json.parse(redis.get(merge_check.cache_key + ":#{VERSION}"))
           end
         end

spec/lib/gitlab/merge_requests/mergeability/redis_interface_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-RSpec.describe Gitlab::MergeRequests::Mergeability::RedisInterface, :clean_gitlab_redis_shared_state do
+RSpec.describe Gitlab::MergeRequests::Mergeability::RedisInterface, :clean_gitlab_redis_cache do
   subject(:redis_interface) { described_class.new }
 
   let(:merge_check) { double(cache_key: '13') }
@@ -11,17 +11,17 @@ RSpec.describe Gitlab::MergeRequests::Mergeability::RedisInterface, :clean_gitla
 
   describe '#save_check' do
     it 'saves the hash' do
-      expect(Gitlab::Redis::SharedState.with { |redis| redis.get(expected_key) }).to be_nil
+      expect(Gitlab::Redis::Cache.with { |redis| redis.get(expected_key) }).to be_nil
 
       redis_interface.save_check(merge_check: merge_check, result_hash: result_hash)
 
-      expect(Gitlab::Redis::SharedState.with { |redis| redis.get(expected_key) }).to eq result_hash.to_json
+      expect(Gitlab::Redis::Cache.with { |redis| redis.get(expected_key) }).to eq result_hash.to_json
     end
   end
 
   describe '#retrieve_check' do
     it 'returns the hash' do
-      Gitlab::Redis::SharedState.with { |redis| redis.set(expected_key, result_hash.to_json) }
+      Gitlab::Redis::Cache.with { |redis| redis.set(expected_key, result_hash.to_json) }
 
       expect(redis_interface.retrieve_check(merge_check: merge_check)).to eq result_hash
     end