This fixes https://github.com/flutter/flutter/issues/145766

The output of the pub command changed slightly with this change: https://dart.googlesource.com/pub/+/2179b765aa9071386be02d408b3c3caa82af98f5

Update the tests to be tolerant of the directory path being surrounded by backticks (or not) so that we are compatible with the current and upcoming implementation.