User limit enforcement (#26511)

* Added hard limits when creating user

* Added check to user activation

* Added missing check for licensed servers

* Fix i18n

* Fixed style order

* Added a separate hard limit along with existing 10k user soft limit

* For CI

* Fixing flaky test, hopefully

* Added tests

server/public/model/limits.go

@@ -4,6 +4,7 @@
 package model
 
 type UserLimits struct {
-	MaxUsersLimit   int64 `json:"maxUsersLimit"`   // max number of users allowed
-	ActiveUserCount int64 `json:"activeUserCount"` // actual number of active users on server. Active = non deleted
+	MaxUsersLimit     int64 `json:"maxUsersLimit"`     // soft limit for max number of users.
+	MaxUsersHardLimit int64 `json:"maxUsersHardLimit"` // hard limit for max number of active users.
+	ActiveUserCount   int64 `json:"activeUserCount"`   // actual number of active users on server. Active = non deleted
 }