[Backport 2.x] Remove minimum constraint on OpenSearch hosts to allow empty host and refactor status API to not include OpenSearch status when host is empty

[opensearch-trigger-bot]

Backport 8e1ec99 from #4701.

[codecov]

Codecov Report

Merging #4802 (ab640f8) into 2.x (d8f156f) will decrease coverage by 0.01%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##              2.x    #4802      +/-   ##
==========================================
- Coverage   66.12%   66.12%   -0.01%     
==========================================
  Files        3315     3315              
  Lines       63909    63913       +4     
  Branches    10126    10128       +2     
==========================================
+ Hits        42259    42260       +1     
+ Misses      19170    19168       -2     
- Partials     2480     2485       +5     

Flag	Coverage Δ
Linux_1	34.77% <ø> (ø)
Linux_2	55.10% <83.33%> (+<0.01%)	⬆️
Linux_3	43.02% <0.00%> (-0.02%)	⬇️
Linux_4	35.08% <0.00%> (-0.01%)	⬇️
Windows_1	34.79% <ø> (ø)
Windows_2	55.07% <83.33%> (+<0.01%)	⬆️
Windows_3	43.02% <0.00%> (-0.01%)	⬇️
Windows_4	35.08% <0.00%> (-0.01%)	⬇️

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

Files Changed	Coverage Δ
src/core/server/opensearch/opensearch_config.ts	93.58% <ø> (ø)
src/core/server/opensearch/status.ts	70.00% <0.00%> (-7.78%)	⬇️
...rc/core/server/opensearch/client/cluster_client.ts	84.21% <100.00%> (ø)
src/core/server/opensearch/opensearch_service.ts	84.61% <100.00%> (+1.28%)	⬆️

... and 3 files with indirect coverage changes