[krbdev.mit.edu #8191] remove a lingering leash reference

[Benjamin Kaduk via RT]

We are trying to rebrand the GUI as "MIT Kerberos.exe" and remove mentions of "leash".

Commit 58122fec56a87ca7f88052f6b55f90b94ce1c386 on master fixes an instance of this, and 
should get pulled up to 1.13