Preserving indices causes seqNo to increase for jobs that aren't full…

[dbbaughe]

…y cleaned up

Issue #, if available:

Description of changes:
We preserve indices between tests and the seq_no can increase from other operations happening in the test suite from other tests, so just assert that it is less than instead of exactly 1 less than.

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 #397 (470f1b0) into master (cf7881f) will decrease coverage by 0.06%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #397      +/-   ##
============================================
- Coverage     77.35%   77.28%   -0.07%     
  Complexity     1510     1510              
============================================
  Files           196      196              
  Lines          7784     7784              
  Branches       1244     1244              
============================================
- Hits           6021     6016       -5     
- Misses         1086     1089       +3     
- Partials        677      679       +2     

Impacted Files	Coverage Δ	Complexity Δ
...nt/indexstatemanagement/model/destination/Chime.kt	40.90% <0.00%> (-13.64%)	2.00% <0.00%> (-2.00%)
...anagement/indexstatemanagement/model/Transition.kt	63.07% <0.00%> (-4.62%)	5.00% <0.00%> (ø%)
...icsearch/indexmanagement/IndexManagementIndices.kt	55.00% <0.00%> (-3.34%)	9.00% <0.00%> (ø%)
...nt/indexstatemanagement/model/destination/Slack.kt	54.54% <0.00%> (+13.63%)	4.00% <0.00%> (+2.00%)

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