[docs] Fix formatting in admin/verifier.rst

[steveburnett]

Description

Fixes doc build error

/Users/steveburnett/Documents/GitHub/presto/presto-docs/src/main/sphinx/admin/verifier.rst:229: WARNING: Bullet list ends without a blank line; unexpected unindent.

Motivation and Context

Builds on work in #23090, #23033, #22876, #22985, and #23210.

Like the doc build errors I fixed in the other PRs, these errors don't stop the build but they're annoying, and these are easy and low-risk fixes.

Impact

Documentation builds.

Test Plan

Local doc build.

Before:

• /Users/steveburnett/Documents/GitHub/presto/presto-docs/src/main/sphinx/admin/verifier.rst:229: WARNING: Bullet list ends without a blank line; unexpected unindent.
• build succeeded, 20 warnings.

After:

• WARNING does not appear
• build succeeded, 19 warnings.

Contributor checklist

• Please make sure your submission complies with our development, formatting, commit message, and attribution guidelines.
• PR description addresses the issue accurately and concisely. If the change is non-trivial, a GitHub Issue is referenced.
• Documented new properties (with its default value), SQL syntax, functions, or other functionality.
• If release notes are required, they follow the release notes guidelines.
• Adequate tests were added if applicable.
• CI passed.

Release Notes

== NO RELEASE NOTE ==

[kiersten-stokes]

LGTM!