[Backport 2.x] Log io.netty.internal.tcnative.SSLContext availability warning only when OpenSSL is explicitly enabled but not available

[opensearch-trigger-bot]

Backport 4aa7b1c from #4901.

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.

Project coverage is 63.87%. Comparing base (7efe29b) to head (68ece4f).
Report is 4 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...rg/opensearch/security/ssl/SslSettingsManager.java	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##              2.x    #4906   +/-   ##
=======================================
  Coverage   63.87%   63.87%           
=======================================
  Files         330      330           
  Lines       23136    23142    +6     
  Branches     3747     3750    +3     
=======================================
+ Hits        14777    14782    +5     
  Misses       6527     6527           
- Partials     1832     1833    +1     

Files with missing lines	Coverage Δ
...rg/opensearch/security/ssl/SslSettingsManager.java	74.35% <87.50%> (+0.35%)	⬆️