Fix #1334: add retry + sleep to github team-repo sync

[achantavy]

Summary

Describe your changes.

Adds a retry with sleep to _get_team_repos_for_multiple_teams because we have seen the GitHub GraphQL API sometimes return None for fields that are not supposed to be None.

Related issues or links

Include links to relevant issues or other pages.

• github sync nonetype error when listing repo-teams #1334

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Added unit tests.

Checklist

• Update/add unit or integration tests

If you are modifying or implementing an intel module:

• Update the schema and readme
• Use the NodeSchema data model

[heryxpc]

Trying to understand the Python magic here.
If team_repos.nodes == None then the for condition will break before assigning any element from the iterable to repo?

[achantavy]

If team_repos.nodes is None, then the for loop will iterate through the empty list. See this:

>>> derp = {'a': [1,2,3], 'b': None}
>>> for r in derp['a'] or []:
...   print(r)
...
1
2
3
>>> for r in derp['b'] or []:
...   print(r)
...
# prints nothing