Commitlog test: remove some hardcoded assumptions on segment IDs
Commitlog test: remove some hardcoded assumptions on segment IDs

To enable changing the ID generation scheme.

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