MM-10640 Set EnableUserCreation to true by default (#8815)

* Set EnableUserCreation to true by default

* Fix argument type to FormatBool

* Convert EnableUserCreation instances to pointer

* Convert to boolean in tests also

* Set value of pointer to be false

* Convert remaining EnableUserCreation instances to pointer

api4/oauth.go

@@ -563,7 +563,7 @@ func signupWithOAuth(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if !c.App.Config().TeamSettings.EnableUserCreation {
+	if !*c.App.Config().TeamSettings.EnableUserCreation {
 		utils.RenderWebError(w, r, http.StatusBadRequest, url.Values{
 			"message": []string{utils.T("api.oauth.singup_with_oauth.disabled.app_error")},
 		}, c.App.AsymmetricSigningKey())