Fix index pattern data source reference not updated in sample data

[wanglam]

Description

This PR is for fixing #6850 , there are two changes in this PR.

1. Add back references update for index pattern saved objects when import sample data
2. Add unit tests to verify references has been updated when generate sample data by data source method

Issues Resolved

#6850

Screenshot

Now data source connection will be exists in index patterns list after sample data imported.

Testing the changes

1. Checkout the branch code and run yarn osd bootstrap
2. Add data_source.enabled: true to config/opensearch_dashboards.yml
3. Run yarn start --no-base-path start OSD server
4. Add some data source in the data source management page
5. Go to import sample data page select new added data source
   
6. Click first "Add data" button and wait for sample data been imported.
7. Go to the index patterns page, the index patterns will show selected data source like below image
   

Changelog

• fix: Update index pattern references with data source when import sample data

Check List

• All tests pass
  • yarn test:jest
  • yarn test:jest_integration
• New functionality includes testing.
• New functionality has been documented.
• Update CHANGELOG.md
• Commits are signed per the DCO using --signoff

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.38%. Comparing base (8d50974) to head (958cf74).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6851   +/-   ##
=======================================
  Coverage   67.38%   67.38%           
=======================================
  Files        3443     3443           
  Lines       67795    67797    +2     
  Branches    11032    11033    +1     
=======================================
+ Hits        45683    45688    +5     
- Misses      19440    19486   +46     
+ Partials     2672     2623   -49     

Flag	Coverage Δ
Linux_1	33.07% <ø> (ø)
Linux_2	55.12% <ø> (ø)
Linux_3	45.17% <ø> (ø)
Linux_4	34.82% <100.00%> (+0.01%)	⬆️
Windows_1	33.09% <ø> (ø)
Windows_2	55.09% <ø> (ø)
Windows_3	45.19% <ø> (ø)
Windows_4	34.82% <100.00%> (+0.01%)	⬆️

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