storage_service: Reduce time for non-seed node to join the ring
storage_service: Reduce time for non-seed node to join the ring

Waiting for 30 seconds is way too long for testing. Reduce it to 5
seconds.

When we have a proper config system, we can specify in cmdline.

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