Is it possible to disable `execute` in lieu of `exec`?
Community wiki answer:

No, this is not possible. I'd add this as a code quality item to their code reviews.

That said, the root cause of the multiple plans is not the different call syntax. That could also happen with different SET options, etc. Instead look at query plans and the parameterization behavior, and the Query Store (if on 2016+) to see why you are getting different plans.

See also: Slow in the Application, Fast in SSMS? by Erland Sommarskog.