Fixing default compilation size for vsphere

Current sizing fails to compile buildpack_cache with no space left on device.
Reused sizing suggested into https://github.com/cloudfoundry/cf-docs/blob/master/source/docs/running/deploying-cf/vsphere/cloud-foundry-example-manifest.md.
Updating default compilation size to more conservative ones suggested by pivotal vsphere team

See https://github.com/cloudfoundry/cf-release/pull/288#issuecomment-35111444