fix(governance): Fix upgrade_canisters_with_golden_nns_state test

[pietrodimarco-dfinity]

This PR fixes the flaky upgrade_canisters_with_golden_nns_state test by advancing time by one month after the monthly node provider rewards distribution, ensuring that voting rewards are also distributed.
One month advancement has been chosen to keep it consistent with previous implementation of the test.
In addition it removes check on voting rewards from node_provider_remuneration_with_golden_nns_state test.

[github-actions]

This pull request changes code owned by the Governance team. Therefore, make sure that
you have considered the following (for Governance-owned code):

1. Update unreleased_changelog.md (if there are behavior changes, even if they are
   non-breaking).

2. Are there BREAKING changes?

3. Is a data migration needed?

4. Security review?

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5. In the text entry box, respond to each of the numbered items in the previous
   section, declare one of the following:

• Done.

• $REASON_WHY_NO_NEED. E.g. for unreleased_changelog.md, "No
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  behave as before.".

Brief Guide to "Externally Visible" Changes

"Externally visible behavior change" is very often due to some NEW canister API.

Changes to EXISTING APIs are more likely to be "breaking".

If these changes are breaking, make sure that clients know how to migrate, how to
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If your changes are behind a feature flag, then, do NOT add entrie(s) to
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Reference(s)

For a more comprehensive checklist, see here.

GOVERNANCE_CHECKLIST_REMINDER_DEDUP

Done