Currently, when logmon fails to reattach, we will retry reattachment to
the same pid until the task restart specification is exhausted.

Because we cannot clear hook state during error conditions, it is not
possible for us to signal to a future restart that it _shouldn't_
attempt to reattach to the plugin.

Here we revert to explicitly detecting reattachment seperately from a
launch of a new logmon, so we can recover from scenarios where a logmon
plugin has failed.

This is a net improvement over the current hard failure situation, as it
means in the most common case (the pid has gone away), we can recover.

Other reattachment failure modes where the plugin may still be running
could potentially cause a duplicate process, or a subsequent failure to launch
a new plugin.

If there was a duplicate process, it could potentially cause duplicate
logging. This is better than a production workload outage.

If there was a subsequent failure to launch a new plugin, it would fail
in the same (retry until restarts are exhausted) as the current failure
mode.

Co-Authored-By: notnoop <mahmood@notnoop.com>