[lldb][test] Make dependent-modules-nodupe-windows case-insensitive (#198807)
Running the test in containers returns `KERNEL32.DLL` instead of
`kernel32.dll`, which causes the test to fail. Both names point to the
same file. Windows path comparison is case-insensitive. The test is
asserting an OS-level behavior, not a casing convention, so it should
not be case-sensitive.