C++: use GetUniformDouble from distro for LaplaceMechanism
C++: use GetUniformDouble from distro for LaplaceMechanism

PiperOrigin-RevId: 415055992
Change-Id: I0f2761775ac7ce070fbed7655654d362a5a6c96b
GitOrigin-RevId: 4b02b94aae5a720f44e7b2b9806959388f8b6675

google/differential-privacy,google/differential-privacy,google/differential-privacy,google/differential-privacy,google/differential-privacy