On reconnect return the value of db_connect()

[markoheijnen]

Currently db_connect() will get called on reconnect inside db_connect. After that the function continues but could be stopped there too.

[johnbillion]

Makes sense.

[johnbillion]

Should the $allow_bail parameter be passed through, too? Otherwise $allow_bail => false turns into $allow_bail => true when attempting the fallback connection.

[pento]

The return is correct. Core only uses $allow_bail => false when reconnecting, which blocks the fallback attempt. I'm okay with adding it in for other uses, though.

[pento]

In 34478:

WPDB: When attempting to fall back to ext/mysql in db_connect(), return the result of the fall back.

While it doesn't affect Core, we should also be passing the $allow_bail parameter, for anything that uses it differently.

Props markoheijnen, johnbillion.

Fixes #33105.