Add a test that drops a table while there is a counter update operation
ongoing in the table.
The test reproduces issue scylladb/scylla-enterprise#4475 and verifies
it is fixed.
Counter updates break under tablet migration (#18180), and for this
reason they need to be disabled until the problem is fixed.
It's enough to forbid creating a table with counters, as altering a
table without counters already cannot result in the table having
counters:
1) Adding a counter column to a table without counters:
```
cqlsh> ALTER TABLE temp.cf ADD (col_name counter);
ConfigurationException: Cannot add a counter column (col_name) in a non counter column family
```
2) Altering a column to be of the counter type:
```
cqlsh> ALTER TABLE temp.cf ALTER col_name TYPE counter;
ConfigurationException: Cannot change col_name from type int to type counter: types are incompatible.
```
Fixes: #19449
Code in functions.cc creates the different TYPEasblob() and blobasTYPE()
functions for all type names TYPE. The functions for the "counter" type
were skipped, supposedly because "counters are not supported yet". But
counters are supported, so let's add the missing functions.
The code fix is trivial, the tests that verify that the result behaves
like Cassandra took more work.
After this patch, unimplemented::cause::COUNTERS is no longer used
anywhere in the code. I wanted to remove it, but noticed that
unimplemented::cause is a graveyard of unused causes, so decided not
to remove this one either. We should clean it up in a separate patch.
Fixes#14742
Also includes tests for tangently-related issues:
Refs #12607
Refs #14319
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
