gh-36046: Fix sqrt(sqrt(2)) memory leak in ginac numeric.cpp
    
Fix the memory leak when computing the outer sqrt in `sqrt(sqrt(2))`, as
reported on sage devel at https://groups.google.com/g/sage-
devel/c/6zpxQKXtJgk

The unit test is a WIP and depends on
tekknolagi/valgrind#1

- Resolves #33074
    
URL: #36046
Reported by: Volker Braun
Reviewer(s): Matthias Köppe

Author: Release Manager