[BUILD] Make WITH_OTLP_HTTP_SSL_PREVIEW mainstream

[marcalff]

Fixes #2365

Changes

Please provide a brief description of the changes here.

• Promote option WITH_OTLP_HTTP_SSL_PREVIEW from experimental to stable
• Promote option WITH_OTLP_HTTP_SSL_TLS_PREVIEW from experimental to stable
• Change default for both to ON

After this change, SSL and TLS options will be included by default in the build.
It will still be possible to exclude the feature from the build, by setting options to OFF, only in release 1.13.0.

Future planned changes

Once this change is shipped as part of the next release (v1.13.0), a subsequent PR will remove the options entirely for release 1.14.0.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #2378 (8dc908d) into main (231ca4a) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2378      +/-   ##
==========================================
- Coverage   87.43%   87.41%   -0.01%     
==========================================
  Files         199      199              
  Lines        6028     6028              
==========================================
- Hits         5270     5269       -1     
- Misses        758      759       +1     

see 1 file with indirect coverage changes