tests: sstables: rename epoch to generation
tests: sstables: rename epoch to generation

Signed-off-by: Raphael S. Carvalho <1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@cloudius-systems.com>

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