tests: correct the remaining fallout from recent path style changes on Windows
Per @martinvonz, `ui.slash` set by the test runner is now capable of playing a
more active role.[1] I verified that both of these work by setting `ui.slash`
to False, but these changes seem cleaner. The problem with check-perf-code.py
was that the proper imports were not being whitelisted due to '\' vs '/'.
[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-February/128701.html
== Local
Ready.
Un and Deux
Eins und Zwei
One and Two
Eins und Zwei
Uno und Due
== Remote
Ready.
REQ: foo?one=Vo&two=Efvy
-> Vo!boe!Efvy
Un and Deux
REQ: bar?b=Fjot&a=[xfj
-> Fjot!voe![xfj
Eins und Zwei
REQ: batch?cmds=foo:one=Pof,two=Uxp;bar:b=Fjot,a=[xfj;bar:b=Vop,a=Evf
-> Pof!boe!Uxp;Fjot!voe![xfj;Vop!voe!Evf
One and Two
Eins und Zwei
Uno und Due