t9700/test.pl: fix path type expectation on cygwin

t9700/test.pl: fix path type expectation on cygwin

Commit 4ec7ac101b ("t9700: accommodate for Windows paths", 2025-12-17)
changed the type of the absolute path to the git directory from unix to
win32 for both GfW and cygwin. This fixed the test for GfW but causes
new failures on cygwin, since the test expectation is that it uses unix
paths on cygwin. In order to not break cygwin, disable the new code by
removing the "or $^O eq 'cygwin'" sub-expression from the conditional
part of the fix.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>