[EXPORTER] Fix URL in ES exporter, fix ipv6 supporting for http client.

[owent]

Fixes #3079
Fixes #3073

Changes

Please provide a brief description of the changes here.

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

[netlify]

✅ Deploy Preview for opentelemetry-cpp-api-docs canceled.

Name	Link
🔨 Latest commit	ef725c9
🔍 Latest deploy log	https://app.netlify.com/sites/opentelemetry-cpp-api-docs/deploys/67034dfbaf498d00081af20a

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.81%. Comparing base (497eaf4) to head (ef725c9).
Report is 134 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3081      +/-   ##
==========================================
+ Coverage   87.12%   87.81%   +0.69%     
==========================================
  Files         200      195       -5     
  Lines        6109     5968     -141     
==========================================
- Hits         5322     5240      -82     
+ Misses        787      728      -59     

Files with missing lines	Coverage Δ
...include/opentelemetry/ext/http/common/url_parser.h	95.00% <100.00%> (+3.00%)	⬆️

... and 124 files with indirect coverage changes

[lalitb]

Thanks.

[marcalff]

LGTM, thanks for the two fixes.