Change default filterable list results to 25

[chosak]

This commit alters the default pagination size for filterable lists from 10 to 25.

How to test this PR

1. Visit http://localhost:8000/about-us/blog/ and see that 25 results are shown, as opposed to https://www.consumerfinance.gov/about-us/blog/ where only 10 are shown.

TODOs

Assessment of backend performance / database queries associated with this change.

Checklist

• PR has an informative and human-readable title
  • PR titles are used to generate the change log in releases; good ones make that easier to scan.
  • Consider prefixing, e.g., "Mega Menu: fix layout bug", or "Docs: Update Docker installation instructions".
• Changes are limited to a single goal (no scope creep)
• Code follows the standards laid out in the CFPB development guidelines
• Future todos are captured in comments and/or tickets