This MR uses AppLogger

It adds AppLogger in files inside
lib/gitlab directory

It also adds a changelog for the same

Add changelog for the change

Update changelog title

Fix spec failures

changelogs/unreleased/app-logger-19.yml

+---
+title: Use GitLab AppLogger in files in lib/gitlab/*
+merge_request: 41302
+author: Rajendra Kadam
+type: other

lib/gitlab/auth/ldap/person.rb

@@ -57,13 +57,13 @@ module Gitlab
         def self.normalize_uid(uid)
           ::Gitlab::Auth::Ldap::DN.normalize_value(uid)
         rescue ::Gitlab::Auth::Ldap::DN::FormatError => e
-          Rails.logger.info("Returning original UID \"#{uid}\" due to error during normalization attempt: #{e.message}") # rubocop:disable Gitlab/RailsLogger
+          Gitlab::AppLogger.info("Returning original UID \"#{uid}\" due to error during normalization attempt: #{e.message}")
 
           uid
         end
 
         def initialize(entry, provider)
-          Rails.logger.debug { "Instantiating #{self.class.name} with LDIF:\n#{entry.to_ldif}" } # rubocop:disable Gitlab/RailsLogger
+          Gitlab::AppLogger.debug "Instantiating #{self.class.name} with LDIF:\n#{entry.to_ldif}"
           @entry = entry
           @provider = provider
         end

lib/gitlab/background_migration/add_merge_request_diff_commits_count.rb

@@ -9,7 +9,7 @@ module Gitlab
       end
 
       def perform(start_id, stop_id)
-        Rails.logger.info("Setting commits_count for merge request diffs: #{start_id} - #{stop_id}") # rubocop:disable Gitlab/RailsLogger
+        Gitlab::AppLogger.info("Setting commits_count for merge request diffs: #{start_id} - #{stop_id}")
 
         update = '
           commits_count = (