HADOOP-18724. [FOLLOW-UP] cherrypick changes from branch-3.3 backport (#5662)

* move FileContext.copy() onto optLong()
* move FileUtil onto optLong()

This brings trunk into sync with the branch-3.3 changes

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileContext.java

@@ -2231,7 +2231,7 @@ public class FileContext implements PathCapabilities {
         InputStream in = awaitFuture(openFile(qSrc)
             .opt(FS_OPTION_OPENFILE_READ_POLICY,
                 FS_OPTION_OPENFILE_READ_POLICY_WHOLE_FILE)
-            .opt(FS_OPTION_OPENFILE_LENGTH,
+            .optLong(FS_OPTION_OPENFILE_LENGTH,
                 fs.getLen())   // file length hint for object stores
             .build());
         try (OutputStream out = create(qDst, createFlag)) {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileUtil.java

@@ -484,7 +484,7 @@ public class FileUtil {
         in = awaitFuture(srcFS.openFile(src)
             .opt(FS_OPTION_OPENFILE_READ_POLICY,
                 FS_OPTION_OPENFILE_READ_POLICY_WHOLE_FILE)
-            .opt(FS_OPTION_OPENFILE_LENGTH,
+            .optLong(FS_OPTION_OPENFILE_LENGTH,
                 srcStatus.getLen())   // file length hint for object stores
             .build());
         out = dstFS.create(dst, overwrite);