Minor changes to support recovering from replica addition failure

[jsjtzyy]

This PR adds minor changes to resume dynamic replica addition if it failed last time before updating InstanceConfig(clustermap update in Helix). The logic is simple: if diskManager finds there is a existing
directory associated with replica to add, it first deletes it and recreates a new one. (The files in previous directory may not be reliable)

[codecov-io]

Codecov Report

Merging #1382 into master will decrease coverage by 0.01%.
The diff coverage is 62.5%.

@@             Coverage Diff              @@
##             master    #1382      +/-   ##
============================================
- Coverage     72.35%   72.34%   -0.02%     
- Complexity     6867     6868       +1     
============================================
  Files           496      496              
  Lines         38854    38862       +8     
  Branches       4940     4941       +1     
============================================
+ Hits          28113    28114       +1     
- Misses         9383     9388       +5     
- Partials       1358     1360       +2

Impacted Files	Coverage Δ	Complexity Δ
...in/java/com.github.ambry.store/StorageManager.java	88.84% <ø> (ø)	54 <0> (ø)	⬇️
.../main/java/com.github.ambry.store/DiskManager.java	88.28% <62.5%> (-0.84%)	55 <0> (ø)
.../com.github.ambry.network/BlockingChannelInfo.java	80.95% <0%> (-3.18%)	16% <0%> (ø)
...github.ambry.rest/AsyncRequestResponseHandler.java	87.87% <0%> (-2.36%)	21% <0%> (ø)
...b.ambry.network/BlockingChannelConnectionPool.java	73.68% <0%> (-2.11%)	11% <0%> (-1%)
...ain/java/com.github.ambry.router/PutOperation.java	91.4% <0%> (-0.5%)	115% <0%> (-1%)
...in/java/com.github.ambry.store/BlobStoreStats.java	71.04% <0%> (ø)	103% <0%> (ø)	⬇️
...c/main/java/com.github.ambry.network/Selector.java	79% <0%> (+0.78%)	78% <0%> (+1%)	⬆️
...va/com.github.ambry.replication/ReplicaThread.java	87.54% <0%> (+0.92%)	95% <0%> (+2%)	⬆️
...java/com.github.ambry.store/CompactionManager.java	92.26% <0%> (+2.38%)	25% <0%> (ø)	⬇️

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[ankagrawal]

LGTM