Revert "Guarantee datasource read api is strong consistent read (#1815)"

[dreamer-89]

This reverts commit f38ffed.

Description

This change reverts the commit f38ffed as

1. With Segment Replication - Support realtime reads with GET requests OpenSearch#8536, core now supports realtime reads with get/mget APIs. Thus, if strong reads are desired plugin can use get/mget queries. get/mget is recommended over _primary based routing preference in order to reduce load on primary.
2. Existing OpenSearchDataSourceMetadataStorage.java uses match_all & term based search queries which does not provide strong reads and thus as part of Compatibility with segment replication #1801 there was no need to perform _primary based routing.

Issues Resolved

Relates: #1801

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

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

Merging #2013 (9c17fcd) into main (b3fd4c4) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #2013      +/-   ##
============================================
- Coverage     97.30%   97.30%   -0.01%     
  Complexity     4623     4623              
============================================
  Files           407      407              
  Lines         11935    11934       -1     
  Branches        828      828              
============================================
- Hits          11613    11612       -1     
  Misses          315      315              
  Partials          7        7              

Flag	Coverage Δ
sql-engine	97.30% <ø> (-0.01%)	⬇️

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

Files Changed	Coverage Δ
...s/storage/OpenSearchDataSourceMetadataStorage.java	98.75% <ø> (-0.01%)	⬇️

[Yury-Fridlyand]

Thank you for detailed description!