trigger: log error in triggers that does not throw an error

Now on_access_denied and on_schema_init triggers do not throw error,
so it just sinks into oblivion, which is not good because a thrown error
indicates that something went wrong and database administrator should be
definitely notified about it.

The commit makes Tarantool log errors thrown from these triggers with
error level. Also, the commit adds a test checking if all triggers are
either raise an error or log it.

Closes #9309

@TarantoolBot document
Title: Mention that triggers are guaranteed to throw an error or log it

Now all triggers are either have a direct impact on the execution flow
(e.g. close a connection or throw an error) or print a message to error
log when they throw an error.

We have a separate entry for triggers in Tarantool documentation, which
lists the properties of the triggers - I think it's a perfect place for
this new property.