refactor: remove Core plugin version checker logic

Author: breedloj

plugins/core/jetbrains-community/resources/META-INF/aws.toolkit.core.xml

@@ -11,7 +11,6 @@
     </extensionPoints>
 
     <extensions defaultExtensionNs="com.intellij">
-        <applicationInitializedListener implementation="software.aws.toolkits.jetbrains.PluginVersionChecker"/>
         <httpRequestHandler implementation="software.aws.toolkits.jetbrains.core.credentials.sso.pkce.ToolkitOAuthCallbackHandler"/>
         <httpRequestHandler implementation="software.aws.toolkits.jetbrains.core.credentials.sso.pkce.ToolkitOAuthCallbackResultService"/>
 
@@ -81,9 +80,6 @@
         <registryKey key="aws.toolkit.notification.endpoint" description="Endpoint for AWS Toolkit notifications"
                      defaultValue="https://idetoolkits-hostedfiles.amazonaws.com/Notifications/Jetbrains/combined/2.x.json" restartRequired="true"/>
 
-
-        <notificationGroup id="aws.plugin.version.mismatch" displayType="STICKY_BALLOON" key="aws.settings.title"/>
-
         <webHelpProvider implementation="software.aws.toolkits.jetbrains.core.help.HelpIdTranslator"/>
     </extensions>