Remove remaining deprecated codecov package usage

[jmbowman]

Seeing openedx/credentials#2298 go by, I realized that we still have a few packages using the obsolete NPM & PyPI packages for codecov. These should be removed, and the code switched over to the new coverage data upload workflow if that hasn't already been done. A search for "codecov in the repo health dashboard yielded:

• edx/gesmarter-api-clients (PyPI)
• edx/learning-assistant (PyPI)
• openedx/django-splash (PyPI)
• openedx/edx-when (PyPI)
• openedx/frontend-app-profile (NPM)
• openedx/help-tokens (PyPI)

[zubairshakoorarbisoft]

I've created 5 PR for the PyPI and not for openedx/frontend-app-profile because codecov does not exist in package.json:

1. Codecov package removed openedx/edx-when#224
2. Rremove codecov package learning-assistant#43
3. Codecov pacakge removed openedx-unsupported/django-splash#158
4. Remove codecov package openedx/help-tokens#174
5. Remove codecov package getsmarter-api-clients#22