github actions: mount docker sock for contrib tests

[rmfitzpatrick]

Description:
Fixing a bug - Adding a docker daemon domain socket volume to the contrib tests container to prevent a failure uncovered by open-telemetry/opentelemetry-collector-contrib@3dfb709.

Example failure: https://github.com/open-telemetry/opentelemetry-collector/runs/4719103326?check_suite_focus=true

Link to tracking Issue:
open-telemetry/opentelemetry-collector-contrib#7023

[codecov]

Codecov Report

Merging #4643 (673041e) into main (60823e2) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #4643   +/-   ##
=======================================
  Coverage   90.46%   90.46%           
=======================================
  Files         181      181           
  Lines       10611    10611           
=======================================
  Hits         9599     9599           
  Misses        788      788           
  Partials      224      224           

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[bogdandrutu]

@rmfitzpatrick does not seem to fix ...

[rmfitzpatrick]

I'm thinking that circleci's setup_remote_docker option adds the container users to the docker group via exec since it has no members by default in cimg/go.

[rmfitzpatrick]

superseded by open-telemetry/opentelemetry-collector-contrib#7056