Chore: add setting to skip org assignment for external users (#34834) (#45692)

* Chore: add setting to skip org assignment for external users

Introduce 'skip_org_role_update_sync' setting to skip any kind of org assignment during the login of external users.
As a consequence manual organization assignments won't be overridden during the upsert of an external user.

Part of #22605

* Chore: Rename skip_org_role_update_sync to oauth_skip_org_role_update_sync and relocate it to auth section

* Chore: replace global setting access where possible

(cherry picked from commit 6beba5a049)

Co-authored-by: baez90 <peter.kurfer@googlemail.com>

pkg/setting/setting.go

@@ -393,9 +393,10 @@ type Cfg struct {
 	DefaultTheme string
 	HomePage     string
 
-	AutoAssignOrg     bool
-	AutoAssignOrgId   int
-	AutoAssignOrgRole string
+	AutoAssignOrg              bool
+	AutoAssignOrgId            int
+	AutoAssignOrgRole          string
+	OAuthSkipOrgRoleUpdateSync bool
 
 	// ExpressionsEnabled specifies whether expressions are enabled.
 	ExpressionsEnabled bool
@@ -1256,6 +1257,7 @@ func readAuthSettings(iniFile *ini.File, cfg *Cfg) (err error) {
 	OAuthAutoLogin = auth.Key("oauth_auto_login").MustBool(false)
 	cfg.OAuthCookieMaxAge = auth.Key("oauth_state_cookie_max_age").MustInt(600)
 	SignoutRedirectUrl = valueAsString(auth, "signout_redirect_url", "")
+	cfg.OAuthSkipOrgRoleUpdateSync = auth.Key("oauth_skip_org_role_update_sync").MustBool(false)
 
 	// SigV4
 	SigV4AuthEnabled = auth.Key("sigv4_auth_enabled").MustBool(false)