Use `version` from ActiveSupport::Cache::Store

* Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/331297
* Follow-up for:
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/64723#note_617721967

ActiveSupport::Cache::Store offers `version` attribute for cache
records. We can use it instead of a custom versioning strategy.

https://api.rubyonrails.org/classes/ActiveSupport/Cache/Store.html#method-i-fetch

lib/api/helpers/caching.rb

@@ -11,12 +11,10 @@ module API
       include Gitlab::Cache::Helpers
       # @return [Hash]
       DEFAULT_CACHE_OPTIONS = {
-        race_condition_ttl: 5.seconds
+        race_condition_ttl: 5.seconds,
+        version: 1
       }.freeze
 
-      # @return Integer
-      VERSION = 1
-
       # @return [Array]
       PAGINATION_HEADERS = %w[X-Per-Page X-Page X-Next-Page X-Prev-Page Link X-Total X-Total-Pages].freeze
 
@@ -81,7 +79,7 @@ module API
       def cache_action(key, **custom_cache_opts)
         cache_opts = apply_default_cache_options(custom_cache_opts)
 
-        json, cached_headers = cache.fetch([key, VERSION], **cache_opts) do
+        json, cached_headers = cache.fetch(key, **cache_opts) do
           response = yield
 
           cached_body = response.is_a?(Gitlab::Json::PrecompiledJson) ? response.to_s : Gitlab::Json.dump(response.as_json)

spec/lib/api/helpers/caching_spec.rb

@@ -81,7 +81,7 @@ RSpec.describe API::Helpers::Caching, :use_clean_rails_redis_caching do
       expected_kwargs = described_class::DEFAULT_CACHE_OPTIONS.merge(kwargs)
 
       expect(expensive_thing).to receive(:do_very_expensive_action).once
-      expect(instance.cache).to receive(:fetch).with([cache_key, 1], **expected_kwargs).exactly(5).times.and_call_original
+      expect(instance.cache).to receive(:fetch).with(cache_key, **expected_kwargs).exactly(5).times.and_call_original
 
       5.times { perform }
     end
@@ -96,6 +96,16 @@ RSpec.describe API::Helpers::Caching, :use_clean_rails_redis_caching do
       expect(nested_call.to_s).to eq(subject.to_s)
     end
 
+    context 'Cache versioning' do
+      it 'returns cache based on version parameter' do
+        result_1 = instance.cache_action(cache_key, **kwargs.merge(version: 1)) { 'Cache 1' }
+        result_2 = instance.cache_action(cache_key, **kwargs.merge(version: 2)) { 'Cache 2' }
+
+        expect(result_1.to_s).to eq('Cache 1'.to_json)
+        expect(result_2.to_s).to eq('Cache 2'.to_json)
+      end
+    end
+
     context 'Cache for pagination headers' do
       described_class::PAGINATION_HEADERS.each do |pagination_header|
         context pagination_header do