ConsistOfProtos matcher returns true if input is not a slice

[arianaw66]

Match implementation: https://github.com/solo-io/solo-kit/blob/v0.21.0/test/matchers/proto.go#L147

Uses result from:

solo-kit/test/matchers/proto.go

Line 198 in d7292e8

return result, true

, which perhaps should return result, false?