Precalculate String() for fuzzed Quantity

Avoids biasing serialization results where the value is assumed to
be in canonical form already.

pkg/api/testing/fuzzer.go

@@ -195,6 +195,8 @@ func FuzzerFor(t *testing.T, version unversioned.GroupVersion, src rand.Source)
 			randomQuantity := func() resource.Quantity {
 				var q resource.Quantity
 				c.Fuzz(&q)
+				// precalc the string for benchmarking purposes
+				_ = q.String()
 				return q
 			}
 			q.Limits = make(api.ResourceList)