ENG-5298: Fix double deletion when both elastic context and COW context are in use.
ENG-5298: Fix double deletion when both elastic context and COW context are in
use.

If a tuple is pending delete by the COW context, the elatic context shouldn't
try to delete it again. Let the COW context take care of it after it's safely
scanned.

ingted/voltdb,wolffcm/voltdb,migue/voltdb,migue/voltdb,paulmartel/voltdb,zuowang/voltdb,wolffcm/voltdb,simonzhangsm/voltdb,kumarrus/voltdb,zuowang/voltdb,zuowang/voltdb,wolffcm/voltdb,zuowang/voltdb,flybird119/voltdb,simonzhangsm/voltdb,kumarrus/voltdb,migue/voltdb,flybird119/voltdb,creative-quant/voltdb,VoltDB/voltdb,creative-quant/voltdb,migue/voltdb,creative-quant/voltdb,ingted/voltdb,creative-quant/voltdb,paulmartel/voltdb,simonzhangsm/voltdb,zuowang/voltdb,flybird119/voltdb,ingted/voltdb,paulmartel/voltdb,wolffcm/voltdb,migue/voltdb,zuowang/voltdb,simonzhangsm/voltdb,kumarrus/voltdb,VoltDB/voltdb,VoltDB/voltdb,wolffcm/voltdb,deerwalk/voltdb,paulmartel/voltdb,zuowang/voltdb,simonzhangsm/voltdb,simonzhangsm/voltdb,wolffcm/voltdb,flybird119/voltdb,flybird119/voltdb,migue/voltdb,migue/voltdb,kumarrus/voltdb,deerwalk/voltdb,creative-quant/voltdb,kumarrus/voltdb,simonzhangsm/voltdb,kumarrus/voltdb,zuowang/voltdb,deerwalk/voltdb,paulmartel/voltdb,ingted/voltdb,wolffcm/voltdb,deerwalk/voltdb,deerwalk/voltdb,deerwalk/voltdb,paulmartel/voltdb,deerwalk/voltdb,ingted/voltdb,flybird119/voltdb,deerwalk/voltdb,kumarrus/voltdb,ingted/voltdb,ingted/voltdb,creative-quant/voltdb,VoltDB/voltdb,paulmartel/voltdb,migue/voltdb,wolffcm/voltdb,kumarrus/voltdb,ingted/voltdb,VoltDB/voltdb,creative-quant/voltdb,flybird119/voltdb,VoltDB/voltdb,creative-quant/voltdb,simonzhangsm/voltdb,flybird119/voltdb,VoltDB/voltdb,paulmartel/voltdb