MM-27149: optimize initBasic (#15063)

* MM-27149: optimize initBasic

Mostly, all tests just needed the user initialization part and not
the channel and group creation. So we move the user initialization inside
the Setup call. This avoids unnecessary DB calls which take around 250-300ms
on average.

And we make the login requests concurrently to shave off a few more ms.
According to my tests, the 2 login calls take 140 ms on average, which
shaves off 70ms.

So approximately, we shave off 350ms per test. And there are 114 occurences
of these. So around 39 seconds.

* make initlogin only for Setup/SetupEnterprise

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/oauth_test.go

@@ -14,7 +14,7 @@ import (
 )
 
 func TestCreateOAuthApp(t *testing.T) {
-	th := Setup(t).InitBasic()
+	th := Setup(t)
 	defer th.TearDown()
 	Client := th.Client
 	AdminClient := th.SystemAdminClient
@@ -188,7 +188,7 @@ func TestUpdateOAuthApp(t *testing.T) {
 }
 
 func TestGetOAuthApps(t *testing.T) {
-	th := Setup(t).InitBasic()
+	th := Setup(t)
 	defer th.TearDown()
 	Client := th.Client
 	AdminClient := th.SystemAdminClient
@@ -254,7 +254,7 @@ func TestGetOAuthApps(t *testing.T) {
 }
 
 func TestGetOAuthApp(t *testing.T) {
-	th := Setup(t).InitBasic()
+	th := Setup(t)
 	defer th.TearDown()
 	Client := th.Client
 	AdminClient := th.SystemAdminClient
@@ -318,7 +318,7 @@ func TestGetOAuthApp(t *testing.T) {
 }
 
 func TestGetOAuthAppInfo(t *testing.T) {
-	th := Setup(t).InitBasic()
+	th := Setup(t)
 	defer th.TearDown()
 	Client := th.Client
 	AdminClient := th.SystemAdminClient
@@ -382,7 +382,7 @@ func TestGetOAuthAppInfo(t *testing.T) {
 }
 
 func TestDeleteOAuthApp(t *testing.T) {
-	th := Setup(t).InitBasic()
+	th := Setup(t)
 	defer th.TearDown()
 	Client := th.Client
 	AdminClient := th.SystemAdminClient
@@ -449,7 +449,7 @@ func TestDeleteOAuthApp(t *testing.T) {
 }
 
 func TestRegenerateOAuthAppSecret(t *testing.T) {
-	th := Setup(t).InitBasic()
+	th := Setup(t)
 	defer th.TearDown()
 	Client := th.Client
 	AdminClient := th.SystemAdminClient