Specify golang web process using absolute path.
Specify golang web process using absolute path.

PiperOrigin-RevId: 308272163
Change-Id: I9a4b6ba414dadb02d31a9d683f2119535bcfd422

GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks