fix(net): optimize activeNodes node adding logic

[317787106]

What does this PR do?
Add fastForwardNode to activeNodes only if it is not exist.

Why are these changes required?
Fix the bug of activeNodes' size continuously growing problem.

This PR has been tested by:

• Unit Tests
• Manual Testing

Follow up

Extra details

[codecov-commenter]

Codecov Report

Merging #4994 (9e086c7) into release_v4.7.1 (b169228) will increase coverage by 0.14%.
The diff coverage is 0.00%.

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@@                 Coverage Diff                  @@
##             release_v4.7.1    #4994      +/-   ##
====================================================
+ Coverage             54.59%   54.74%   +0.14%     
- Complexity             8201     8225      +24     
====================================================
  Files                   840      840              
  Lines                 49642    49644       +2     
  Branches               5447     5448       +1     
====================================================
+ Hits                  27102    27176      +74     
+ Misses                20394    20329      -65     
+ Partials               2146     2139       -7     

Impacted Files	Coverage Δ
.../org/tron/core/net/service/relay/RelayService.java	21.81% <0.00%> (-0.41%)	⬇️
...rc/main/java/org/tron/core/vm/program/Program.java	67.37% <0.00%> (+0.08%)	⬆️
...ain/java/org/tron/core/services/RpcApiService.java	4.95% <0.00%> (+0.12%)	⬆️
...ork/src/main/java/org/tron/core/trie/TrieImpl.java	58.24% <0.00%> (+0.35%)	⬆️
...mework/src/main/java/org/tron/core/db/Manager.java	53.07% <0.00%> (+0.37%)	⬆️
.../src/main/java/org/tron/core/ChainBaseManager.java	90.62% <0.00%> (+1.25%)	⬆️
...in/java/org/tron/common/zksnark/JLibrustzcash.java	53.84% <0.00%> (+1.39%)	⬆️
.../src/main/java/org/tron/core/config/args/Args.java	59.92% <0.00%> (+1.76%)	⬆️
...ain/java/org/tron/core/db/backup/BackupDbUtil.java	85.10% <0.00%> (+2.12%)	⬆️
...ain/java/org/tron/consensus/dpos/StateManager.java	51.02% <0.00%> (+4.08%)	⬆️
... and 8 more

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