[Backport] [2.x] Ensure support of the transport-nio by security plugin (HTTP) (#16474)

[reta]

Backport of #16474 to 2.x

[github-actions]

❌ Gradle check result for dad027f: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[reta]

@andrross if you don't mind this backport please, thank you!

[github-actions]

✅ Gradle check result for dad027f: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 68.91892% with 23 lines in your changes missing coverage. Please review.

Project coverage is 71.76%. Comparing base (2fa8370) to head (dad027f).
Report is 3 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...ain/java/org/opensearch/http/nio/ssl/SslUtils.java	0.00%	13 Missing ⚠️
...rg/opensearch/http/nio/NioHttpServerTransport.java	87.17%	3 Missing and 2 partials ⚠️
...g/opensearch/transport/nio/NioTransportPlugin.java	0.00%	3 Missing ⚠️
.../org/opensearch/http/nio/HttpReadWriteHandler.java	77.77%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #16565      +/-   ##
============================================
- Coverage     71.95%   71.76%   -0.20%     
+ Complexity    65440    65387      -53     
============================================
  Files          5312     5313       +1     
  Lines        305033   305098      +65     
  Branches      44443    44452       +9     
============================================
- Hits         219475   218939     -536     
- Misses        67269    67912     +643     
+ Partials      18289    18247      -42     

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