Add migration for backfilling traversal_ids in blobs and wiki blobs

What does this MR do and why?

Describe in detail what your merge request does and why.

Backfills the traversal_ids for blobs and wiki blobs in the main index, more details in the issue #351381 (closed)

Time for completion estimate calculation (internal link): 278 hours (may take a little longer due to having to work through each project). Indexing will not be paused during the migration.

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Run the following query to get the blobs and wiki_blobs with missing traversal_ids

{
  "size": 0,
  "query": {
    "bool": {
      "must_not": {
        "exists": {
          "field": "traversal_ids"
        }
      },
      "must": {
        "terms": {
          "type": [
            "blob",
            "wiki_blob"
          ]
        }
      }
    }
  },
  "aggs": {
    "my-agg-name": {
      "terms": {
        "size": 1000,
        "field": "project_id"
      }
    }
  }
}

2. Make sure advanced search is enabled and you run the migration from rails console by entering the following lines:

require File.expand_path('ee/elastic/migrate/20221221110300_add_traversal_ids_in_blobs_and_wiki_blobs.rb')
BackfillTraversalIdsToBlobsAndWikiBlobs.new(20221221110300).migrate

3. Run the query again in ES to verify that there are no records with misssing traversal_ids

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #351381 (closed)

ee/elastic/migrate/20221221110300_backfill_traversal_ids_to_blobs_and_wiki_blobs.rb

@@ -22,10 +22,10 @@ def migrate
       end
 
       if task_status['completed']
-        log "Updating traversal_ids in original index is completed for task_id:#{task_id}"
+        log "Updating traversal_ids in original index is completed for task_id: #{task_id}"
         set_migration_state(task_id: nil)
       else
-        log "Updating traversal_ids in original index is still in progress for task_id:#{task_id}"
+        log "Updating traversal_ids in original index is still in progress for task_id: #{task_id}"
       end
 
       return
@@ -39,10 +39,10 @@ def migrate
     log "Searching for the projects with missing traversal_ids"
     project_ids = projects_with_missing_traversal_ids
     log "Found #{project_ids.size} projects with missing traversal_ids"
-    project_ids.each do |project_id|
-      update_by_query(Project.find(project_id))
+    begin
+      update_by_query(Project.find(project_ids[0])) unless project_ids.empty?
     rescue ActiveRecord::RecordNotFound
-      log "Project not found: #{project_id}"
+      log "Project not found: #{project_ids[0]}"
     end
   end
 
@@ -58,6 +58,7 @@ def completed?
   private
 
   def update_by_query(project)
+    log "Launching update query for project #{project.id}"
     response = client.update_by_query(
       index: helper.target_name,
       body: {
@@ -85,7 +86,7 @@ def update_by_query(project)
     end
 
     task_id = response['task']
-    log "Adding traversal_ids to original index is started with task_id:#{task_id}"
+    log "Adding traversal_ids to original index is started with task_id: #{task_id}"
 
     set_migration_state(
       task_id: task_id