Upgrade OTel to v1.0.0-RC3

[XSAM]

• Upgrade OTel to v1.0.0-RC3.
• Remove the dependency of the go.opentelemetry.io/otel/oteltest package.

[codecov]

Codecov Report

Merging #29 (473489b) into main (dd44876) will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##            main     #29   +/-   ##
=====================================
  Coverage   81.6%   81.6%           
=====================================
  Files         11      11           
  Lines        299     299           
=====================================
  Hits         244     244           
  Misses        45      45           
  Partials      10      10           

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