sstables: don't cast composites to bytes_view
sstables: don't cast composites to bytes_view

Now that we can write composites directly, we no longer should use bytes_view.

As a matter of fact, write(out, ... bytes_view(x)) is wrong, because our write
function can't handle rvalue-references very well. Doing both those things, we
can fix a tricky bug that showed up recently in our stress tests.

Signed-off-by: Glauber Costa <f8b79557d19b40666ebe336545a0b6178af65685@cloudius-systems.com>

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