Change CLI TLS configuration to HTTP2

[krapie]

What this PR does / why we need it:

Change CLI TLS configuration to HTTP2.

There were two reasons for this bug:

• CLI was not requesting with HTTPS (default scheme was HTTP).
• HTTP/TLS version between AWS LB/TG(HTTP/2) and CLI request(HTTP/1.1) was different.

Therefore, I have updated:

• Default HTTP scheme configuration to either HTTP or HTTPS based on client configuration(--insecure flag).
• HTTP client transport protocol to explicit HTTP2.

Which issue(s) this PR fixes:

Fixes #733

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Additional documentation:

Checklist:

• Added relevant tests or not required
• Didn't break anything

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (8e6e205) 49.27% compared to head (5736314) 49.25%.

Files	Patch %	Lines
client/client.go	0.00%	6 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #742      +/-   ##
==========================================
- Coverage   49.27%   49.25%   -0.02%     
==========================================
  Files          69       69              
  Lines       10081    10084       +3     
==========================================
  Hits         4967     4967              
- Misses       4598     4601       +3     
  Partials      516      516              

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[hackerwins]

Thanks for your contribution.