Issue #3255740: Allow overriding of auth provider settings.

src/Entity/SalesforceAuthConfig.php

@@ -113,6 +113,10 @@ class SalesforceAuthConfig extends ConfigEntityBase implements EntityWithPluginC
    *   Provider settings.
    */
   public function getProviderSettings() {
+  // Get config overrides.
+  $this->provider_settings = $this->authManager()
+      ->getConfig($this->id())
+      ->get('provider_settings');
     return $this->provider_settings + ['id' => $this->id()];
   }