Need to fix issue with less top sites shown than expected

[data-sync-user]

See details here: https://github.com/mozilla-mobile/firefox-ios/pull/23918

Note: I notice a discrepancy in the previous PR in that in landscape we are showing 7 tiles instead of 8. Most likely due to my change in using environment.container.effectiveContentSize instead of view.size like the previous code. Will create a separate ticket to address this.

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