Fixes incorrect field in mappings check that ignores sub fields

[dbbaughe]

Issue #, if available:

Description of changes:

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Merging #343 (f41b852) into master (b43b809) will increase coverage by 0.02%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master     #343      +/-   ##
============================================
+ Coverage     75.85%   75.88%   +0.02%     
- Complexity     1332     1333       +1     
============================================
  Files           182      182              
  Lines          6822     6822              
  Branches       1095     1095              
============================================
+ Hits           5175     5177       +2     
+ Misses         1053     1052       -1     
+ Partials        594      593       -1     

Impacted Files	Coverage Δ	Complexity Δ
...arch/indexmanagement/rollup/RollupMapperService.kt	59.45% <0.00%> (ø)	25.00 <0.00> (+1.00)
...orelasticsearch/indexmanagement/util/IndexUtils.kt	76.92% <ø> (ø)	1.00 <0.00> (ø)
...anagement/indexstatemanagement/model/Transition.kt	67.69% <0.00%> (+3.07%)	5.00% <0.00%> (ø%)

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