help: Update "View your starred messages" section for Flutter launch.

Deletes static/images/help/mobile-star-icon.svg as it's no
longer used.

Part of #34748.

help/include/view-starred-messages.md

@@ -18,8 +18,9 @@
 
 {tab|mobile}
 
-1. Tap the **Starred messages**
-   (<img src="/static/images/help/mobile-star-icon.svg" alt="star" class="help-center-icon"/>)
-   tab at the top of the app.
+1. Tap the **Menu** (<i class="zulip-icon zulip-icon-mobile-menu mobile-help"></i>)
+   tab in the bottom right corner of the app.
+
+1. Tap <i class="zulip-icon zulip-icon-star mobile-help"></i> **Starred messages**.
 
 {end_tabs}

static/images/help/mobile-star-icon.svg

@@ -1,3 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="#6492fd" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather feather-star">
-    <polygon points="12 2 15.09 8.26 22 9.27 17 14.14 18.18 21.02 12 17.77 5.82 21.02 7 14.14 2 9.27 8.91 8.26 12 2"></polygon>
-</svg>