[DOCFIX] Fix the HDFS document
[DOCFIX] Fix the HDFS document

### What changes are proposed in this pull request?

The default port of HDFS web UI is 9870 in the version over 3.0.0

### Why are the changes needed?

Please clarify why the changes are needed. For instance,
1. If not, the User will think that he configured the HDFS incorrectly.

### Does this PR introduce any user facing changes?

no

pr-link: Alluxio/alluxio#14864
change-id: cid-f0b97fc9be0ecbd26c53ee00c84b7d9cc223f388
Alluxio/alluxio,wwjiang007/alluxio,Alluxio/alluxio,wwjiang007/alluxio,Alluxio/alluxio,wwjiang007/alluxio,Alluxio/alluxio,wwjiang007/alluxio,wwjiang007/alluxio,wwjiang007/alluxio,Alluxio/alluxio,Alluxio/alluxio,Alluxio/alluxio,Alluxio/alluxio,wwjiang007/alluxio,Alluxio/alluxio,Alluxio/alluxio,wwjiang007/alluxio,wwjiang007/alluxio,wwjiang007/alluxio