Move to Paketo full tag builder image

[qu1queee]

This is a follow up from #406

I tested if the container images that we build with Paketo can be deployed
with the bionic stack via test branch.

Moving from builder:latest to builder:full means that we are gonna stop
running on top of a cflinuxfs3 stack in favor of a bionic stack.

Paketo community mentioned that the bionic stack have parity with cflinuxfs3,
therefore this is a safe change, plus the deployment validations I did.

[zhangtbj]

Thanks for the verification!

Let us switch to use full image tag.

@xiujuan95 will continue communicating with Paketo community to see if they can switch latest image tag to full officially.

It doesn't make sense if they will not update full-cf stack but still using latest based on it, most of users will use latest directly.

/lgtm
/approve

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[xiujuan95]

@zhangtbj @qu1queee Just for your info, community said they will switch latest to point to the full builder soon:https://paketobuildpacks.slack.com/archives/CULAS8ACD/p1602517320018900?thread_ts=1600670275.004100&cid=CULAS8ACD