Avoid sticky containers in importing screen for now

Section content is being obscured under the headings, causing settings
not to be seen, and text to appear in unusual places like under the
importing bar at the bottom. Until a better solution can be found, this
should allow things to be shown properly.

https://forums.ankiweb.net/t/anki-2-1-55-beta-3/24295/27

ts/import-csv/Header.svelte

@@ -3,16 +3,12 @@ Copyright: Ankitects Pty Ltd and contributors
 License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 -->
 <script lang="ts">
-    import StickyContainer from "../components/StickyContainer.svelte";
-
     export let heading: string;
 </script>
 
-<StickyContainer --sticky-border="var(--border)" --sticky-borders="0px 0 1px">
-    <h1>
-        {heading}
-    </h1>
-</StickyContainer>
+<h1>
+    {heading}
+</h1>
 
 <style lang="scss">
     h1 {