Send callback requests to Rails

What does this MR do and why?

Send the callback to Rails on indexing. In addition to that rename the DiskStatus to DiskStats

How to set up and validate locally

• Run indexer in GDK mode
• Open the rails console

bundle exec rails c

• Setup Zoekt for a namespace

::Feature.enable(:index_code_with_zoekt)
::Feature.enable(:search_code_with_zoekt)
zoekt_node = ::Search::Zoekt::Node.find_or_create_by!(index_base_url: 'http://127.0.0.1:6080/', search_base_url: 'http://127.0.0.1:6090/', uuid: '00000000-0000-0000-0000-000000000000')
namespace = Namespace.find_by_full_path("flightjs") # Some namespace you want to enable
::Zoekt::IndexedNamespace.find_or_create_by!(node: zoekt_node, namespace: namespace.root_ancestor)

• Add Callback in the request

diff --git a/ee/lib/gitlab/search/zoekt/client.rb b/ee/lib/gitlab/search/zoekt/client.rb
index 85d881f81530..4f0550a8a395 100644
--- a/ee/lib/gitlab/search/zoekt/client.rb
+++ b/ee/lib/gitlab/search/zoekt/client.rb
@@ -153,7 +153,11 @@ def indexing_payload(project, force:)
             },
             RepoId: project.id,
             FileSizeLimit: Gitlab::CurrentSettings.elasticsearch_indexed_file_size_limit_kb.kilobytes,
-            Timeout: "#{INDEXING_TIMEOUT_S}s"
+            Timeout: "#{INDEXING_TIMEOUT_S}s",
+            Callback: {
+              name: 'index',
+              payload: {}
+            }
           }
 
           payload[:Force] = force if force

• Run the Zoekt indexer

Zoekt::IndexerWorker.new.perform(namespace.id)

• Tail the log file log/api_json.log

tail -f log/api_json.log

• You must see in your log something like this:

{"time":"2023-12-07T13:04:38.072Z","severity":"INFO","duration_s":0.00052,"db_duration_s":0.0,"view_duration_s":0.00052,"status":415,"method":"POST","path":"/api/v4/internal/search/zoekt/ee43cf9f-093c-4606-92d9-0f6703434b51/callback","params":[{"key":"{\"name\":\"index\",\"payload\":{\"index_file_count\":2,\"size_in_bytes\":1165580},\"success\":true}","value":null}],"host":"localhost","remote_ip":"127.0.0.1","ua":"Go-http-client/1.1","route":"/api/:version/internal/search/zoekt/:uuid/callback","queue_duration_s":0.014746,"redis_calls":6,"redis_duration_s":0.000586,"redis_read_bytes":1189,"redis_write_bytes":385,"redis_feature_flag_calls":6,"redis_feature_flag_duration_s":0.000586,"redis_feature_flag_read_bytes":1189,"redis_feature_flag_write_bytes":385,"db_count":1,"db_write_count":0,"db_cached_count":0,"db_replica_count":0,"db_primary_count":1,"db_main_count":1,"db_ci_count":0,"db_main_replica_count":0,"db_ci_replica_count":0,"db_replica_cached_count":0,"db_primary_cached_count":0,"db_main_cached_count":0,"db_ci_cached_count":0,"db_main_replica_cached_count":0,"db_ci_replica_cached_count":0,"db_replica_wal_count":0,"db_primary_wal_count":0,"db_main_wal_count":0,"db_ci_wal_count":0,"db_main_replica_wal_count":0,"db_ci_replica_wal_count":0,"db_replica_wal_cached_count":0,"db_primary_wal_cached_count":0,"db_main_wal_cached_count":0,"db_ci_wal_cached_count":0,"db_main_replica_wal_cached_count":0,"db_ci_replica_wal_cached_count":0,"db_replica_duration_s":0.0,"db_primary_duration_s":0.003,"db_main_duration_s":0.003,"db_ci_duration_s":0.0,"db_main_replica_duration_s":0.0,"db_ci_replica_duration_s":0.0,"cpu_s":0.013248,"pid":59451,"worker_id":"puma_0","rate_limiting_gates":[],"correlation_id":"01HH262MN4YP1K14E37VATJ179","meta.remote_ip":"127.0.0.1","meta.client_id":"ip/127.0.0.1","content_length":"88","request_urgency":"medium","target_duration_s":0.5}

Closes #25 (closed)