Missing the original I920e1bc134d1283e2019f4389a5491e9b746cca0
implementation, also filter the per-team PTL electorates to only
include OpenStack Foundation Individual Members. The previous change
did this correctly for the full (Technical Committee) electorate but
failed to apply a similar conditional constraint to Project Team
Lead electoral rolls.
Change-Id: I03e90e5c512ee463cfcc49f147ff523806ae05c7
Story: #2001094
Task: #4877