tests: lines with largefile .* file://$TESTTMP also match on windows

on windows, largefile paths are written as "file:///C:/temp/...", corresponding
to "file:///$TESTTMP/..." (all three slashes shown).
But on posix systems they are written as "file:///tmp/..." corresponding to
"file://$TESTTMP/..." (only two slashes shown).

Write the glob "file:/*/" to match both versions.