DEV: Log a warning message when a MiniScheduler scheduled job is stuck (#28258)

This commit adds a `MiniSchedulerLongRunningJobLogger` class which will
poll every 60 seconds for mini_scheduler jobs which are stuck. When it
detects that a job is stuck, it will log a warning message with the
current backtrace of the thread that is executing the job.

Note that for scheduled jobs which are executed at a frequency of less
than 30 minutes, we will log when the job has been executing for 30
minutes.

For scheduled jobs executed at a frequency of less than 2 hours, we will
log when the job has been executing for a duration greater than its
specified frequency.

For scheduled jobs executed at a frequency greater than 2 hours, we will
log as long as the job has been executing for more than 2 hours.

config/initializers/100-sidekiq.rb

@@ -3,6 +3,7 @@
 require "sidekiq/pausable"
 require "sidekiq_logster_reporter"
 require "sidekiq_long_running_job_logger"
+require "mini_scheduler_long_running_job_logger"
 
 Sidekiq.configure_client { |config| config.redis = Discourse.sidekiq_redis_config }
 
@@ -47,6 +48,11 @@ if Sidekiq.server?
     if !scheduler_hostname || scheduler_hostname.split(",").include?(Discourse.os_hostname)
       begin
         MiniScheduler.start(workers: GlobalSetting.mini_scheduler_workers)
+
+        MiniSchedulerLongRunningJobLogger.new(
+          poll_interval_seconds:
+            ENV["DISCOURSE_MINI_SCHEDULER_LONG_RUNNING_JOB_LOGGER_POLL_INTERVAL_SECONDS"],
+        ).start
       rescue MiniScheduler::DistributedMutex::Timeout
         sleep 5
         retry