bug#81516: 31.0.91; delete-file-local-variable(-prop-line) should delete "Local Variables" block (prop-line)

> From: Daniel Mendler <[email protected]>
> Cc: [email protected],  [email protected],  [email protected]
> Date: Thu, 30 Jul 2026 09:31:29 +0200
> 
> Eli Zaretskii <[email protected]> writes:
> 
> > Thanks.  Could we please have tests for this, including in cases where
> > the prop line doesn't exist, or looks similar, but isn't a prop line?
> 
> I have not found tests for file local variables. Are there any? I can
> write a bunch of basic tests but this will take a little more time.

In this case, just testing the situation where all the variables are
deleted would be enough.  It would be good to have additional tests
for the file-local variables in general, but that doesn't have to be
part of this patch.