fix(frontend): fix token removing after conversation leaving

Regression of: #9068

Signed-off-by: Grigorii Shartsev <grigorii.shartsev@nextcloud.com>

src/components/LeftSidebar/LeftSidebar.vue

@@ -609,6 +609,9 @@ export default {
 			}
 			if (from.name === 'conversation') {
 				this.$store.dispatch('leaveConversation', { token: from.params.token })
+				if (to.name !== 'conversation') {
+					this.$store.dispatch('updateToken', '')
+				}
 			}
 			if (to.name === 'conversation') {
 				this.$store.dispatch('joinConversation', { token: to.params.token })