update put route when flattening result index

[jackiehanyang]

Description

update put route to enable flatten result index in put route

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 5 lines in your changes missing coverage. Please review.

Project coverage is 81.55%. Comparing base (70eb089) to head (5f62c7f).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../rest/handler/AbstractTimeSeriesActionHandler.java	80.00%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1409      +/-   ##
============================================
+ Coverage     81.53%   81.55%   +0.02%     
+ Complexity     5857     5856       -1     
============================================
  Files           533      533              
  Lines         23675    23664      -11     
  Branches       2375     2374       -1     
============================================
- Hits          19303    19300       -3     
+ Misses         3207     3199       -8     
  Partials       1165     1165              

Flag	Coverage Δ
plugin	81.55% <80.00%> (+0.02%)	⬆️

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

Files with missing lines	Coverage Δ
...g/opensearch/timeseries/util/RestHandlerUtils.java	67.46% <ø> (+3.64%)	⬆️
.../rest/handler/AbstractTimeSeriesActionHandler.java	93.07% <80.00%> (-0.20%)	⬇️

... and 11 files with indirect coverage changes