Investigate need for TROOT::EndOfProcessCleanups in PyROOT

[vepadulano]

As discussed at https://github.com/root-project/root/pull/10753#issuecomment-1155514143 , the current way we run TROOT::EndOfProcessCleanups twice when using PyROOT is necessary, but we don't understand why. The change in the PR removed the double use of the function and the original reproducer still works. It would be nice to have test coverage for this particular pattern used in PyROOT.