[grid] Silent fail on invalid log level

Fixing issue where providing an invalid log level to Grid will fail silently.

Since the logger is not yet configured a stacktrace with the exception is printed to console and we continue since the default log level is already configured.

Fixes #15790

Author: Oxilod

java/src/org/openqa/selenium/grid/log/LoggingOptions.java

@@ -76,7 +76,9 @@ public void setLoggingLevel() {
     try {
       level = Level.parse(configLevel.toUpperCase(Locale.ROOT));
     } catch (IllegalArgumentException e) {
-      throw new ConfigException("Unable to determine log level from " + configLevel);
+      // Logger is not configured yet
+      new ConfigException("Unable to determine log level from " + configLevel +
+       ". Using default " + DEFAULT_LOG_LEVEL).printStackTrace();
     }
   }