gossip: Run remove_endpoint inside seastar::async context
gossip: Run remove_endpoint inside seastar::async context

on_remove is now under seastar::async context.

kjniemi/scylla,rentongzhang/scylla,phonkee/scylla,bowlofstew/scylla,victorbriz/scylla,gwicke/scylla,gwicke/scylla,capturePointer/scylla,acbellini/scylla,rentongzhang/scylla,asias/scylla,eklitzke/scylla,eklitzke/scylla,stamhe/scylla,victorbriz/scylla,asias/scylla,bowlofstew/scylla,tempbottle/scylla,avikivity/scylla,respu/scylla,glommer/scylla,avikivity/scylla,victorbriz/scylla,capturePointer/scylla,aruanruan/scylla,stamhe/scylla,raphaelsc/scylla,shaunstanislaus/scylla,respu/scylla,glommer/scylla,asias/scylla,respu/scylla,scylladb/scylla,senseb/scylla,scylladb/scylla,guiquanz/scylla,kangkot/scylla,scylladb/scylla,guiquanz/scylla,acbellini/scylla,eklitzke/scylla,shaunstanislaus/scylla,tempbottle/scylla,rluta/scylla,justintung/scylla,wildinto/scylla,rluta/scylla,stamhe/scylla,linearregression/scylla,duarten/scylla,phonkee/scylla,senseb/scylla,avikivity/scylla,capturePointer/scylla,aruanruan/scylla,linearregression/scylla,phonkee/scylla,justintung/scylla,scylladb/scylla,glommer/scylla,raphaelsc/scylla,aruanruan/scylla,linearregression/scylla,kangkot/scylla,kjniemi/scylla,gwicke/scylla,dwdm/scylla,wildinto/scylla,duarten/scylla,wildinto/scylla,tempbottle/scylla,raphaelsc/scylla,duarten/scylla,dwdm/scylla,kjniemi/scylla,kangkot/scylla,dwdm/scylla,shaunstanislaus/scylla,justintung/scylla,rentongzhang/scylla,guiquanz/scylla,acbellini/scylla,senseb/scylla,bowlofstew/scylla,rluta/scylla