[SDK-514] Disable use demo toggle in setup guide (#131)

## [SDK-514](https://ready-player-me.atlassian.net/browse/SDK-514)

## Description

- Disable use demo toggle in setup guide

.github/CODEOWNERS

@@ -2,5 +2,4 @@
 # the repo. Unless a later match takes precedence,
 # @HarrisonHough, @rYuuk will be requested for
 # review when someone opens a pull request.
-*       @HarrisonHough @rYuuk
-
+*       @readyplayerme/onboarding-integrations

Editor/UI/EditorWindows/SetupGuide/SetupGuide.uxml

@@ -13,7 +13,7 @@
                 <ui:Label tabindex="-1" text="(https://studio.readyplayer.me)" display-tooltip-when-elided="true" name="StudioUrl" class="link" style="margin-left: 15px; margin-right: 15px; white-space: normal; margin-top: 0; color: rgb(0, 104, 255);" />
             </ui:VisualElement>
             <ReadyPlayerMe.Core.Editor.SubdomainTemplate class="SubdomainTemplate" style="margin-top: 15px; flex-shrink: 0;" />
-            <ui:Toggle label="I don&apos;t have an account. Use demo subdomain instead." name="UseDemoSubdomainToggle" style="margin-left: 15px; margin-right: 15px; flex-direction: row-reverse; align-items: center; justify-content: space-between; align-self: flex-start; margin-top: 15px; margin-bottom: 15px;" />
+            <ui:Toggle label="I don&apos;t have an account. Use demo subdomain instead." name="UseDemoSubdomainToggle" style="margin-left: 15px; margin-right: 15px; flex-direction: row-reverse; align-items: center; justify-content: space-between; align-self: flex-start; margin-top: 15px; margin-bottom: 15px; display: none;" />
         </ui:VisualElement>
         <ui:VisualElement name="AnalyticsPanel" style="flex-grow: 0; background-color: rgba(0, 0, 0, 0); margin-top: 0; height: 230px; flex-shrink: 0; display: flex; width: 500px;">
             <ui:VisualElement name="Heading" class="heading" style="flex-grow: 0; background-color: rgba(0, 0, 0, 0);">