original design prepended a namespace to the beginning of uuid.
this scoped the uuid to a namespace but it is technically invalid.
this patch drops the behaviour of prepending string. rather, it
takes the namespace, hashes it, and uses uuid v5 to generate valid
uuid based on that namespace
Change-Id: Ibde222c91522fa3c4a1720b6a8da81dac31560b9
Closes-Bug: #1504889
42b2926c0a