[Backport 3.1] Fix incorrect task state handling in ForecastRunOnceTransportAction

[opensearch-trigger-bot]

Backport 0a127da from #1489.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.39%. Comparing base (cf5d9ea) to head (b27f188).
Report is 1 commits behind head on 3.1.

Files with missing lines	Patch %	Lines
...cast/transport/ForecastRunOnceTransportAction.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                3.1    #1490      +/-   ##
============================================
- Coverage     81.45%   81.39%   -0.07%     
+ Complexity     5983     5975       -8     
============================================
  Files           536      536              
  Lines         24204    24204              
  Branches       2443     2443              
============================================
- Hits          19716    19701      -15     
- Misses         3278     3290      +12     
- Partials       1210     1213       +3     

Flag	Coverage Δ
plugin	81.39% <50.00%> (-0.07%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
.../org/opensearch/forecast/model/ForecastResult.java	77.83% <ø> (ø)
...ava/org/opensearch/timeseries/util/ParseUtils.java	76.37% <100.00%> (ø)
...cast/transport/ForecastRunOnceTransportAction.java	51.97% <0.00%> (ø)

... and 5 files with indirect coverage changes

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