fix(Keycloak): Wait until user created (#1535)

Author: HofmeisterAn

src/Testcontainers.Keycloak/KeycloakBuilder.cs

@@ -89,6 +89,7 @@ public override KeycloakContainer Build()
         var isMajorVersionGreaterOrEqual25 = image.MatchLatestOrNightly() || image.MatchVersion(predicate);
 
         var waitStrategy = Wait.ForUnixContainer()
+            .UntilMessageIsLogged("Added user '[^']+' to realm '[^']+'|Created temporary admin user with username \\S+")
             .UntilHttpRequestIsSucceeded(request =>
                 request.ForPath("/health/ready").ForPort(isMajorVersionGreaterOrEqual25 ? KeycloakHealthPort : KeycloakPort));