tests: Stop distributed db when test ends
tests: Stop distributed db when test ends

Fixes:

cql_query_test: ./core/distributed.hh:150: distributed<Service>::~distributed() [with Service = database]: Assertion `_instances.empty()' failed.

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