add a test that writes to a table concurrently with dropping a column,
where the table has CDC enabled with preimage.
the test reproduces issue #26340 where this results in a malformed
sstable.
When we drop a column from a CDC log table, we set the column drop
timestamp a few seconds into the future. This can cause unexpected
problems if a user tries to recreate a CDC column too soon, before
the drop timestamp has passed.
To prevent this issue, when creating a CDC column we check its
creation timestamp against the existing drop timestamp, if any, and
fail with an informative error if the recreation attempt is too soon.
Add a simple test verifying our changes for the compatible CDC schema.
The test checks we can write to a table with CDC enabled after ALTER and
after node restart.
in the CDC log transformer, when augmenting a base mutation, use the CDC
log schema that is compatible with the base schema, if set.
Now that the base schema has a pointer to its CDC schema, we can use it
instead of getting the current schema from the db, which may not be
compatible with the base schema.
The compatible CDC schema may not be set if the cluster is not using
raft mode for schema. In this case, we maintain the previous behavior.
previously the test set tablets to disabled because cdc wasn't supported
with tablets. now we can change this to use the default to enable it to
run with either tablets or vnodes.
