Add default replica capacity in resource config

[justinlin-linkedin]

Add default replicas capacity in resource config and use this replica capacity to create new partition

[codecov-commenter]

Codecov Report

Patch coverage: 70.96% and project coverage change: +0.02% 🎉

Comparison is base (827d592) 72.88% compared to head (d024e70) 72.90%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2531      +/-   ##
============================================
+ Coverage     72.88%   72.90%   +0.02%     
- Complexity    11237    11244       +7     
============================================
  Files           792      792              
  Lines         63701    63729      +28     
  Branches       7788     7794       +6     
============================================
+ Hits          46426    46461      +35     
+ Misses        14725    14721       -4     
+ Partials       2550     2547       -3     

Files Changed	Coverage Δ
...a/com/github/ambry/clustermap/ClusterMapUtils.java	92.13% <ø> (+0.32%)	⬆️
...ub/ambry/clustermap/HelixBootstrapUpgradeUtil.java	70.46% <0.00%> (-0.15%)	⬇️
...m/github/ambry/clustermap/HelixClusterManager.java	89.29% <78.57%> (+1.27%)	⬆️

... and 21 files with indirect coverage changes

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[SophieGuo410]

lgtm