[web] Fix: `sendConfirmationEmail` promise (!!!) (#19629)
* Fix `sendConfirmationEmail` promise (!!!)
* Fix: No nested promises, and `sendConfirmationEmail`->`sendReconfirmationEmail`
* Add integration test on `/user/emails/send-reconfirmation`
* Update integration test: use the previously generated token
GitOrigin-RevId: f6386abeb06888351eec22fbcb1d3c614ff5c5c5