Fix HTML elements size in search tab

Specifying a height/width value might cut the displayed text or
obstruct centering the text in the button, so let it auto decide
instead.
Closes #11553.

src/webui/www/private/views/search.html

@@ -11,17 +11,14 @@
 
     #categorySelect {
         width: 150px;
-        height: 20px;
     }
 
     #pluginsSelect {
         width: 150px;
-        height: 20px;
     }
 
     #startSearchButton {
         width: 90px;
-        height: 20px;
     }
 
     #searchResultsNoPlugins {
@@ -49,7 +46,6 @@
     }
 
     #manageSearchPlugins {
-        line-height: 1.5em;
         float: right;
     }