Make HttpClientGitHubConnector the default for Java 11+

[bitwiseman]

Description

Fixes #754
Fixes #1202
Fixes #1085
Fixes #1086

Before submitting a PR:

We love getting PRs, but we hate asking people for the same basic changes every time.

• Push your changes to a branch other than main. Create your PR from that branch.
• Add JavaDocs and other comments
• Write tests that run and pass in CI. See CONTRIBUTING.md for details on how to capture snapshot data.
• Run mvn -D enable-ci clean install site locally. If this command doesn't succeed, your change will not pass CI.

When creating a PR:

• Fill in the "Description" above.
• Enable "Allow edits from maintainers".

[codecov]

Codecov Report

Merging #1314 (6c21554) into main (65d6de2) will decrease coverage by 0.05%.
The diff coverage is 44.44%.

@@             Coverage Diff              @@
##               main    #1314      +/-   ##
============================================
- Coverage     77.97%   77.92%   -0.06%     
- Complexity     2015     2016       +1     
============================================
  Files           198      198              
  Lines          6216     6224       +8     
  Branches        355      355              
============================================
+ Hits           4847     4850       +3     
- Misses         1160     1164       +4     
- Partials        209      210       +1     

Impacted Files	Coverage Δ
src/main/java/org/kohsuke/github/GitHubClient.java	88.88% <33.33%> (-1.36%)	⬇️
...ohsuke/github/internal/DefaultGitHubConnector.java	86.66% <66.66%> (-5.65%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 65d6de2...6c21554. Read the comment docs.