help: Remove "Status and availability" mobile tabs.

The ability to view, set, edit a user's status, or to toggle invisible
mode are not yet implemented for the initial launch of the Flutter
mobile app, so we remove the legacy React Native app instructions.

Deletes static/images/help/mobile-x-icon.svg as it is no
longer used.

This feature is tracked in:
https://github.com/zulip/zulip-flutter/issues/197
https://github.com/zulip/zulip-flutter/issues/198
https://github.com/zulip/zulip-flutter/issues/1578

Part of #34748.

help/status-and-availability.md

@@ -32,17 +32,6 @@ You can set a status emoji, status message, or both.
 
 {!set-status.md!}
 
-{tab|mobile}
-
-{!mobile-profile-menu.md!}
-
-1. Tap **Set your status**.
-
-1. Tap to select one of the common statuses, *or* choose any emoji and/or
-   write a short message.
-
-1. Tap **Save**.
-
 {end_tabs}
 
 ### Clear a status
@@ -61,18 +50,6 @@ You can set a status emoji, status message, or both.
 
 {!clear-status.md!}
 
-{tab|mobile}
-
-{!mobile-profile-menu.md!}
-
-1. Tap **Set your status**.
-
-1. Tap the **x**
-   (<img src="/static/images/help/mobile-x-icon.svg" alt="x" class="help-center-icon"/>)
-   to the right of your current status.
-
-1. Tap **Save**.
-
 {end_tabs}
 
 ### View a status
@@ -95,15 +72,6 @@ and compose box. Status emoji and status messages are also shown on
     sent to view their status in their **user card**, or configure status text
     to always be shown in the right sidebar.
 
-{tab|mobile}
-
-1. Tap on a user's profile picture or name to open their profile.
-
-1. Look for their status below the user's role (e.g., Member) if they have one
-   set.
-
-{!mobile-view-user-profile-tip.md!}
-
 {end_tabs}
 
 ### Configure how statuses are displayed
@@ -178,12 +146,6 @@ Your activity will still be included in your organization's [statistics](/help/a
     You can also toggle this setting in the **Account & privacy**
     tab of your **Personal settings** menu.
 
-{tab|mobile}
-
-{!mobile-profile-menu.md!}
-
-1. Toggle **Invisible mode**.
-
 {end_tabs}
 
 ## Related articles

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

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#6492fd" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather feather-x"><line x1="18" y1="6" x2="6" y2="18"></line><line x1="6" y1="6" x2="18" y2="18"></line></svg>