fix(login): improve auth handlers (#7969)

# Which Problems Are Solved

During the implementation of #7486 it was noticed, that projections in
the `auth` database schema could be blocked.
Investigations suggested, that this is due to the use of
[GORM](https://gorm.io/index.html) and it's inability to use an existing
(sql) transaction.
With the improved / simplified handling (see below) there should also be
a minimal improvement in performance, resp. reduced database update
statements.

# How the Problems Are Solved

The handlers in `auth` are exchanged to proper (sql) statements and gorm
usage is removed for any writing part.
To further improve / simplify the handling of the users, a new
`auth.users3` table is created, where only attributes are handled, which
are not yet available from the `projections.users`,
`projections.login_name` and `projections.user_auth_methods` do not
provide. This reduces the events handled in that specific handler by a
lot.

# Additional Changes

None

# Additional Context

relates to #7486

cmd/setup/setup.go

@@ -138,6 +138,7 @@ func Setup(config *Config, steps *Steps, masterKey string) {
 	steps.s23CorrectGlobalUniqueConstraints = &CorrectGlobalUniqueConstraints{dbClient: esPusherDBClient}
 	steps.s24AddActorToAuthTokens = &AddActorToAuthTokens{dbClient: queryDBClient}
 	steps.s25User11AddLowerFieldsToVerifiedEmail = &User11AddLowerFieldsToVerifiedEmail{dbClient: esPusherDBClient}
+	steps.s26AuthUsers3 = &AuthUsers3{dbClient: esPusherDBClient}
 
 	err = projection.Create(ctx, projectionDBClient, eventstoreClient, config.Projections, nil, nil, nil)
 	logging.OnError(err).Fatal("unable to start projections")
@@ -175,6 +176,7 @@ func Setup(config *Config, steps *Steps, masterKey string) {
 		steps.s22ActiveInstancesIndex,
 		steps.s23CorrectGlobalUniqueConstraints,
 		steps.s24AddActorToAuthTokens,
+		steps.s26AuthUsers3,
 	} {
 		mustExecuteMigration(ctx, eventstoreClient, step, "migration failed")
 	}