Election: `submit_unsigned` should be `DispatchClass::Operational`.

[kianenigma]

Follow-up issue: We should make the submit_unsigned be of class DispatchClass::Operational as it is serving an important role in the system and should be treated slightly better.

In this case, the length limit should also be proportional to this.

Originally posted by @kianenigma in #8317 (comment)

[stale]

Hey, is anyone still working on this? Due to the inactivity this issue has been automatically marked as stale. It will be closed if no further activity occurs. Thank you for your contributions.

[kianenigma]

@coriolinus want to close this one too real quick 😄