CL of LOCAL_QUORUM used to be hardcoded into CDC preimage query
and led to an error when number of replicas was lower than CL
would require. The solution here is to link the CLs of writes
to base table with the CLs of CDC reads, so the client will get
the (limited) control over the consistency of preimage SELECTs
(instead of getting error every time).
The algorithm is as follows:
1. If write that caused CDC activity was done with CL = ANY,
then do preimage read with CL = ONE.
2. If write that caused CDC activity was done with CL = ALL,
then do preimage read with CL = QUORUM.
3. SERIAL and LOCAL_SERIAL writes cause preimage read with QUORUM
and LOCAL_QUORUM, respectively.
4. In other cases do preimage read with the same CL as base write.
c70311f73e