Enhancement: Improve logging when de-queuing spooled alert messages

[sjvudp]

While changing the configuration of the mailserver (the old server retired) thing weren't running as expected, so alert messages got queued like this (somewhat older Monit 5.29.0):

[2024-04-16T08:46:20+0200] error    : Cannot connect to [localhost]:25 -- Connection refused
[2024-04-16T08:46:20+0200] error    : Cannot open a connection to the mailserver localhost:25 -- Operation now in progress
[2024-04-16T08:46:20+0200] error    : Mail: SSL server certificate verification error: unable to get local issuer certificate
[2024-04-16T08:46:20+0200] error    : SSL: write error -- error:140840FF:SSL routines:ssl3_connect:unknown state
[2024-04-16T08:46:20+0200] error    : SMTP: Error sending data to the mailserver -- Success
[2024-04-16T08:46:20+0200] info     : Adding event to the queue file /var/lib/monit/1713249980_1c12cf0 for later delivery

At some later time those queued messages were actually sent, but no message was lopgged. I suspect it happened here:

[2024-04-16T10:01:42+0200] info     : Reinitializing monit daemon
[2024-04-16T10:01:42+0200] info     : Reinitializing Monit -- control file '/etc/monitrc'
[2024-04-16T10:01:43+0200] info     : 'REDACTED' Monit reloaded
[2024-04-16T10:01:43+0200] error    : Cannot connect to [localhost]:25 -- Connection refused
[2024-04-16T10:01:43+0200] error    : Cannot open a connection to the mailserver localhost:25 -- Operation now in progress

I think a corresponding message when removing an alert from the queue would be useful.

I should explain that the messages "sent" got lost on the way, and now we are investigating when they had been sent actually.