Disabled downstream workflows

[ianthomas23]

The downstream CI workflows for jupyter_client and ipyparallel are temporarily disabled on the main branch starting with #1414. This is a tracking issue to follow progress on PRs in those downstream projects that need to be merged before the workflows can be enabled here.

• jupyter_client:
  • ipykernel 7 support - take 2 ipyparallel#947
• ipyparallel:
  • Revert test changes of PR 1034 jupyter/jupyter_client#1067
  • Attempt to fix CI jupyter/jupyter_client#1068