Bug 1701756 - Fix stretched navbar images in the search bar preferences UI. r=Gijs,preferences-reviewers

We just need to set `align=start` on `#searchBarVisibleGroup`. There are a
couple of things to note about this:

* The images are stretched only when the Quick Suggest checkbox is visible,
  which it isn't unless the Quick Suggest pref is enabled
* This is broken even without the Quick Suggest checkbox because the two images
  shrink when the window is narrow

Differential Revision: https://phabricator.services.mozilla.com/D110487

browser/components/preferences/search.inc.xhtml

@@ -13,7 +13,7 @@
 
     <groupbox id="searchbarGroup" data-category="paneSearch" hidden="true">
       <label control="searchBarVisibleGroup"><html:h2 data-l10n-id="search-bar-header"/></label>
-      <radiogroup id="searchBarVisibleGroup" preference="browser.search.widget.inNavBar">
+      <radiogroup id="searchBarVisibleGroup" preference="browser.search.widget.inNavBar" align="start">
         <radio id="searchBarHiddenRadio" value="false" data-l10n-id="search-bar-hidden"/>
         <image class="searchBarImage searchBarHiddenImage" role="presentation"/>
         <radio id="searchBarShownRadio" value="true" data-l10n-id="search-bar-shown"/>