use fallback domain if pollDataDAO is unavailable

[apanicker-nflx]

Remove the reliance on PollDataDAO in the critical execution path of a workflow. If the poll data DAO is unavailable, fallback to the last domain in the provided list of domains for a task instead.

[codecov]

Codecov Report

Merging #1712 into dev will increase coverage by 0.03%.
The diff coverage is 62.50%.

@@             Coverage Diff              @@
##                dev    #1712      +/-   ##
============================================
+ Coverage     64.85%   64.89%   +0.03%     
  Complexity     3748     3748              
============================================
  Files           289      289              
  Lines         17844    17847       +3     
  Branches       1614     1614              
============================================
+ Hits          11573    11581       +8     
+ Misses         5455     5450       -5     
  Partials        816      816              

Impacted Files	Coverage Δ	Complexity Δ
...nductor/core/orchestration/ExecutionDAOFacade.java	51.61% <25.00%> (-0.85%)	38.00 <1.00> (ø)
...lix/conductor/core/execution/WorkflowExecutor.java	79.20% <100.00%> (ø)	168.00 <2.00> (ø)
...ctor/core/execution/mapper/DecisionTaskMapper.java	93.87% <100.00%> (ø)	7.00 <0.00> (ø)
...tflix/conductor/dao/dynomite/RedisPollDataDAO.java	96.87% <100.00%> (ø)	8.00 <0.00> (ø)
.../conductor/dao/cassandra/CassandraMetadataDAO.java	59.58% <0.00%> (+1.55%)	25.00% <0.00%> (+1.00%)
...ductor/dao/cassandra/CassandraEventHandlerDAO.java	76.31% <0.00%> (+6.57%)	15.00% <0.00%> (-1.00%)	⬆️

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[coveralls]

Pull Request Test Coverage Report for Build 4191

• 5 of 8 (62.5%) changed or added relevant lines in 4 files are covered.
• 10 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.07%) to 69.395%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
core/src/main/java/com/netflix/conductor/core/orchestration/ExecutionDAOFacade.java	1	4	25.0%

Files with Coverage Reduction	New Missed Lines	%
cassandra-persistence/src/main/java/com/netflix/conductor/dao/cassandra/CassandraEventHandlerDAO.java	2	68.42%
cassandra-persistence/src/main/java/com/netflix/conductor/dao/cassandra/CassandraMetadataDAO.java	8	55.44%

Totals
Change from base Build 4185:	-0.07%
Covered Lines:	12385
Relevant Lines:	17847

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💛 - Coveralls