GetRandomStripe function to randomly select a segment stripe to
audit was using `segment.EncryptedSize/segment.Redundancy.StripeSize()`.
Since integer divsion truncates it leads to skipping last stripe if
its size is less than stripe size. Use `Redundancy.StripeCount` to
get correct stripe count.
Change-Id: Ida09e035be30a21219ab3e1aedd66af8be707d1b
Move ui tests to testsuite/ and introduce a new go.mod.
This prevents cyclic references when building edge binaries for testing.
Change-Id: I613fdc21ef9eaffba2052f6ad973bfa18c7c86bd