[FLINK-10383] [s3] Prevent Hadoop configs in the classpath to seep in…

…to S3 configuration

The S3 connectors are based on a self-contained shaded Hadoop and should not load implicitly
configs from the classpath, like Hadoop does it. Instead, they should only use config value
from the Flink configuration.

flink-filesystems/flink-fs-hadoop-shaded/src/main/java/org/apache/hadoop/conf/Configuration.java

@@ -657,21 +657,7 @@ private void handleDeprecation() {
 	static {
 		// Add default resources
 		addDefaultResource("core-default-shaded.xml");
-		addDefaultResource("core-site.xml");
-
-		// print deprecation warning if hadoop-site.xml is found in classpath
-		ClassLoader cL = Thread.currentThread().getContextClassLoader();
-		if (cL == null) {
-			cL = Configuration.class.getClassLoader();
-		}
-		if (cL.getResource("hadoop-site.xml") != null) {
-			LOG.warn("DEPRECATED: hadoop-site.xml found in the classpath. " +
-					"Usage of hadoop-site.xml is deprecated. Instead use core-site.xml, "
-					+ "mapred-site.xml and hdfs-site.xml to override properties of " +
-					"core-default.xml, mapred-default.xml and hdfs-default.xml " +
-					"respectively");
-			addDefaultResource("hadoop-site.xml");
-		}
+		addDefaultResource("core-default-testing.xml");
 	}
 
 	private Properties properties;