Improve pipeline reload feature.

[mashhurs]

Issue description

There are number of situations which can prevent pipeline(s) from reloading:

• general cases where plugins do not have an ability to shutdown or abort the batch
  • depending on which plugin is being used, users may not get a same expectation. Some plugins, for example http-output aborts the batch and reloads when using PQ but not a case when using memory queue.
  • some plugins internally handles the abort batch. For example, http-output raises PluginInternalQueueLeftoverError when received shutdown and has inflight events. Or, es-output has its own way of handling (raise org.logstash.execution.AbortedBatchException.new if abort_batch_present?) after LS 8.8+ versions.
• specific cases:
  • such as Inputs using schedulers can hang when trying to restart pipelines #16101

Acceptance Criteria

We need to address

• pipeline reload standardization all across the plugins.
• test pipeline-to-pipeline communications