For 16.4: Fix Geo verification state backfill job can exceed batch size

What does this MR do and why?

Describe in detail what merge request is being backported and why

Backports !136275 (merged) to 16.4. For reference, here is the 16.5 backport.

This MR fixes the underlying code so that it does not return a batch that exceeds the specified batch size. This is expected to mitigate memory spikes.

Backport request: https://gitlab.com/gitlab-org/release/tasks/-/issues/7273

Related to #429242 (closed) and #430913 (closed)

MR acceptance checklist

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• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The MR that fixed the bug on the default branch has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the e2e:package-and-test-ee job has either succeeded or been approved by a Software Engineer in Test.

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