[#525][FOLLOWUP] fix: add omitempty tag

[advancedxy]

What changes were proposed in this pull request?

Add omitempty for RPCNodePort and HTTPNodePort

Why are the changes needed?

This is a bug fixes. Otherwise, rss spec cannot omit rpcNodePort and httpNodePort

Does this PR introduce any user-facing change?

No

How was this patch tested?

No need

[codecov-commenter]

Codecov Report

Merging #565 (f5c22f8) into master (f461460) will decrease coverage by 0.36%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #565      +/-   ##
============================================
- Coverage     60.87%   60.51%   -0.36%     
+ Complexity     1796     1567     -229     
============================================
  Files           213      191      -22     
  Lines         12375    10531    -1844     
  Branches       1049      885     -164     
============================================
- Hits           7533     6373    -1160     
+ Misses         4435     3793     -642     
+ Partials        407      365      -42     

Impacted Files	Coverage Δ
...storage/handler/impl/DataSkippableReadHandler.java	83.78% <0.00%> (-2.71%)	⬇️
...ava/org/apache/uniffle/server/ShuffleTaskInfo.java	98.07% <0.00%> (-1.93%)	⬇️
.../apache/uniffle/coordinator/ClientConfManager.java	91.54% <0.00%> (-1.41%)	⬇️
.../java/org/apache/spark/shuffle/RssSparkConfig.java
...k/shuffle/writer/WrappedByteArrayOutputStream.java
...preduce/task/reduce/RssRemoteMergeManagerImpl.java
...e/spark/shuffle/reader/RssShuffleDataIterator.java
...ava/org/apache/spark/shuffle/RssShuffleHandle.java
.../org/apache/spark/shuffle/writer/WriterBuffer.java
...n/java/org/apache/hadoop/mapreduce/RssMRUtils.java
... and 15 more

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[wangao1236]

LGTM