Fix ignore unmapped minimum version

[ryanbogan]

Description

Fixes incorrect minimum required version to use ignore_unmapped functionality

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed as per the DCO using --signoff

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[codecov]

Codecov Report

Merging #1239 (a11644f) into 2.x (def209e) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##                2.x    #1239      +/-   ##
============================================
+ Coverage     85.06%   85.12%   +0.06%     
  Complexity     1187     1187              
============================================
  Files           155      155              
  Lines          4881     4881              
  Branches        450      450              
============================================
+ Hits           4152     4155       +3     
+ Misses          530      527       -3     
  Partials        199      199              

Files	Coverage Δ
.../main/java/org/opensearch/knn/index/IndexUtil.java	61.97% <100.00%> (ø)

... and 1 file with indirect coverage changes

[heemin32]

Shouldn't we push the change to main as well?

[ryanbogan]

Shouldn't we push the change to main as well?

Raising a PR for that shortly

[martin-gaievski]

Shouldn't we push the change to main as well?

+1, we may remove that later from main, but for now it's better to have it in main. FYI, rolling upgrades are supported for all minor versions of current major, plus the last one for the previous major. E.g. if we do 2.12 and then 3.0, then we don't need support for 2.11 in 3.x codeline.

[ryanbogan]

@martin-gaievski @heemin32 looks like main already has the version as 2.11
https://github.com/opensearch-project/k-NN/blob/main/src/main/java/org/opensearch/knn/index/IndexUtil.java#L37C1-L37C1