chore(runtime-node): use mocha dep from monorepo package.json

[blumamir]

Following #2717 , I noticed that all the packages in the repo use mocha from the mono-repo root package.json except for @opentelemetry/instrumentation-runtime-node which is the only one that specify the dependency explicitly.

This PR remove this dependency to align this package with the repo and reduce the modules we need to pull into node_modules

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.47%. Comparing base (197ee04) to head (168360d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2731   +/-   ##
=======================================
  Coverage   91.47%   91.47%           
=======================================
  Files         171      171           
  Lines        8150     8150           
  Branches     1653     1653           
=======================================
  Hits         7455     7455           
  Misses        695      695           

[d4nyll]

Thanks @blumamir!