FIX: Poll wasn't showing all voters (PR #13620)

Partially revert f490a8d39a12ed2c6b125b3380f08b2d1d43ee7f because we aren’t able to load more than the initially preloaded voters.

We were always trying to load the 1st page of voters.

Also removed the “remove users who changed their vote” logic as it was not properly working in multiple choices polls.

cc @nbianca


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