Fix issue in gallery when there's not enough labels to display more than 1 page

[jsomeara]

Resolves #3621

In gallery queries with not enough entries to form more than one page, the gallery system was falsely enabling the next label button and next page button. They should be disabled because there is no next page, and no next label at the end. The issue was that the system did not check if there was enough labels until updateCardsNewPage was called. This was fixed by adding a check in the _init function.

Before/After screenshots (if applicable)

Before:

After:

Testing instructions

1. Find a query that doesn't have enough entries to make a page
2. Verify that the next page and next label (for the last label on the first page) buttons are disabled.

Things to check before submitting the PR

• I've written a descriptive PR title.
• I've included before/after screenshots above.

[misaugstad]

Perfect, thank you!!