ingest: date processor should not fail if timestamp is specified as json number

Closes #26967

Author: martijnvg

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DateProcessor.java

@@ -29,10 +29,10 @@
 import org.joda.time.format.ISODateTimeFormat;
 
 import java.util.ArrayList;
+import java.util.IllformedLocaleException;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
-import java.util.Objects;
 import java.util.function.Function;
 
 public final class DateProcessor extends AbstractProcessor {