[7.x] Add SSL SYSCALL EOF as a lost connection message

[gaelreyrol]

As Laravel get's deployed everywhere and to Clever Cloud, we started to get errors from long running workers trying to execute jobs having DB queries.
When a worker has not executed anything in a while, the first job fails with this error while the next ones runs fine.

SQLSTATE[HY000]: General error: 7 SSL SYSCALL error: EOF detected (SQL: select * from "an_example_table")

Our investigation shows that the connection is closed by the server because it was not used and we fixed it by adding these calls inspired by Heroku's recommandations:

Queue::before(function (JobProcessing $event) {
    DB::connection()->reconnect();
});

Queue::after(function (JobProcessed $event) {
    DB::connection()->disconnect();
});

Queue::failing(function (JobFailed $event) {
    DB::connection()->disconnect();
});

But we tought that Laravel might consider this as a try again message.

PS: Maybe the message is too specific and should be more generic: SSL SYSCALL error: EOF detected and I think it should be backported to 6.x.

Regards

[GrahamCampbell]

Please send this PR to 6.x. :)

[gaelreyrol]

@GrahamCampbell done ! #32697