commitlog: guard commit log replay against reordering
commitlog: guard commit log replay against reordering

After killing scylla in the middle of a write, the next scylla
instance failed to finish commit log replay, showing the following
error message:

scylla: core/future.hh:448: void promise<T>::set_value(A&& ...)
[with A = {}; T = {}]: Assertion `_state' failed.

After a long debug session, I figured out that check_valid_rp() was
triggering the exception replay_position_reordered_exception, which
means replay position reordering.

Looking at 8b9a63a3c6, I noticed that database::apply is guarded
against reodering, but commitlog replay code is not.

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

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