Stop leaking a file handle in a test (#72415)

Files.lines leaks?! When I backported #72277 the tooling caught an issue
with `Paths.get` and one thing led to another and we found the test
leaking a file handle. This fixes that leak.

server/src/test/java/org/elasticsearch/common/xcontent/support/AbstractFilteringTestCase.java

@@ -10,6 +10,7 @@
 
 import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.bytes.BytesReference;
+import org.elasticsearch.common.io.PathUtils;
 import org.elasticsearch.common.util.set.Sets;
 import org.elasticsearch.common.xcontent.XContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
@@ -19,7 +20,6 @@
 import java.net.URISyntaxException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
-import java.nio.file.Path;
 import java.util.Set;
 
 import static java.util.Collections.emptySet;
@@ -1438,10 +1438,10 @@ public void testManyFilters() throws IOException, URISyntaxException {
             .endObject()
             .endObject()
             .endObject();
-        Set<String> manyFilters = Files.lines(
-            Path.of(AbstractFilteringTestCase.class.getResource("many_filters.txt").toURI()),
+        Set<String> manyFilters = Files.readAllLines(
+            PathUtils.get(AbstractFilteringTestCase.class.getResource("many_filters.txt").toURI()),
             StandardCharsets.UTF_8
-        ).filter(s -> false == s.startsWith("#")).collect(toSet());
+        ).stream().filter(s -> false == s.startsWith("#")).collect(toSet());
         testFilter(deep, deep, manyFilters, emptySet());
     }
 }