Bug Report: vtctldclient vreplication commands allow workflows w/o tablet types

[mattlord]

Overview of the Issue

For a VReplication workflow to start, it must be able to use at least one valid tablet type.

Today we allow a user to explicitly (I would assume accidentally) specify an empty string which passes our validation.

We instead should return an error in this case as I cannot think of a valid use case for doing so.

Note
In this case you would have to cancel and re-create the workflow or use workflow update to update the tablet-types value.

Reproduction Steps

git checkout main && make build

cd examples/local

./101_initial_cluster.sh; ./201_customer_tablets.sh

vtctldclient MoveTables --workflow commerce2customer --target-keyspace customer create --source-keyspace commerce --tables "customer,corder" --tablet-types="fake"

vtctldclient MoveTables --workflow commerce2customer --target-keyspace customer create --source-keyspace commerce --tables "customer,corder" --tablet-types=""

vtctldclient workflow --keyspace customer update --workflow commerce2customer --tablet-types=""

Binary Version

vtgate version Version: 19.0.0-SNAPSHOT (Git revision 8575b170183bce389103d451965dc12070f4e36d branch 'main') built on Mon Oct 16 22:17:43 EDT 2023 by matt@pslord.local using go1.21.3 darwin/arm64

Operating System and Environment details

N/A

Log Fragments

No response