[web] Remove unused variables

web-src/src/components/ModalDialogComposer.vue

@@ -106,7 +106,6 @@ export default {
     },
 
     open_tracks() {
-      this.show_details_modal = false
       this.$router.push({
         name: 'music-composer-tracks',
         params: { name: this.composer.name }

web-src/src/pages/PageMusic.vue

@@ -99,7 +99,6 @@ export default {
       recently_added: [],
       recently_played: { items: [] },
       selected_track: {},
-      show_track_details_modal: false
     }
   }
 }