[Nearby] Fix sizing issues with visibility page help section

On the high visibility page, the help text was larger than spec,
and the info icon was getting shrunk down to 15px by flex.

Bug: b/163036847
Change-Id: I8cbc51622100bf5971131cdaae6c5ec1fbdb717a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2481042Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Curt Clemens <cclem@google.com>
Cr-Commit-Position: refs/heads/master@{#819086}

chrome/browser/resources/settings/chromeos/nearby_share_page/nearby_share_high_visibility_page.html

@@ -19,22 +19,23 @@
       }
 
       #help {
-        align-items: center;
+        align-items: flex-start;
         color: var(--google-gray-500);
         display: flex;
         flex-direction: row;
+        font-size: 9px;
+        line-height: 12px;
         margin-inline-end: 24px;
         margin-inline-start: 24px;
         padding: 8px;
       }
 
       #helpText {
-        font-size: .8rem;
-        line-height: .8rem;
         margin: auto;
       }
 
       #infoIcon {
+        flex-shrink: 0;
         height: 20px;
         margin-inline-end: 12px;
         width: 20px;