fix(v-expand-transition): remove height afterLeave
fix(v-expand-transition): remove height afterLeave

if user does not specify a height, it should always be nulled out before and after transition

fixes #4808

vuetifyjs/vuetify,Phlow2001/vuetify,Phlow2001/vuetify,Webifi/vuetify,vuetifyjs/vuetify,vuetifyjs/vuetify,vuetifyjs/vuetify,Phlow2001/vuetify,Phlow2001/vuetify,Webifi/vuetify,Webifi/vuetify