Change ZooKeeperMasterMode.staticPorts() to return Set instead of List

[davidxia]

so later on helios-master won't try to delete the same ZK path multiple times in a single transaction when undeploying a job that uses the same port with different protocols.

[codecov[bot]]

Codecov Report

Merging #1297 into master will increase coverage by 0.03%. The diff coverage is 60.00%.

@@             Coverage Diff              @@
##             master    #1297      +/-   ##
============================================
+ Coverage     53.07%   53.11%   +0.03%     
- Complexity     1657     1659       +2     
============================================
  Files           269      269              
  Lines         13135    13135              
  Branches       1505     1505              
============================================
+ Hits           6971     6976       +5     
+ Misses         5649     5647       -2     
+ Partials        515      512       -3     

[firstway]

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