Remove ptvsd test req (microsoft#6611)

Author: IanMatthewHuff

build/ci/templates/test_phases.yml

@@ -203,7 +203,6 @@ steps:
  python -m pip install -U pip
  python -m pip install numpy
  python -m pip install --upgrade -r ./build/functional-test-requirements.txt
- python -m pip install --upgrade --pre ptvsd
  displayName: 'pip install functional requirements'
  condition: and(succeeded(), eq(variables['NeedsPythonFunctionalReqs'], 'true'))