feat: propagate transaction tag correctly in all scenarios#219

viacheslav-rostovtsev wants to merge 3 commits intogoogleapis:maingoogleapis/ruby-spanner:mainfrom

viacheslav-rostovtsev:dev/virost/fix/mux_transaction_tagviacheslav-rostovtsev/ruby-spanner:dev/virost/fix/mux_transaction_tagCopy head branch name to clipboard