Limit the login size stored in attempt table
As discussed in #5375 (closed), a malicious user could make trytond store a very large login name in the attempt table.
I propose to put a size constraint and to truncate the login received from the outside.
I think a size of 1024 is good enough but of course any installation with a login greater than that will share the login attempt. I don't think it is a problem.
Also I put it as security issue so I think we should backport it to all series but I don't think it deserves a CVE number because there are no data leak nor privilege escalation.