run `make test-v8-updates` as a sub-job of `node-test-commit-v8-linux`

[mmarchini]

As discussed in #1274 and nodejs/node#20783, we should add a sub-job to node-test-commit-v8-linux which runs make test-v8-updates on a Ubuntu 16.04 machine, otherwise tests for missing postmortem metadata and for Linux perf won't run during V8 updates.

[maclover7]

@mmarchini Can you please prepare the full bash script for the job, and then I can drop that into a new job and setup the configuration for you

[mmarchini]

Sure. The script should look like https://github.com/nodejs/build/pull/1329/files, right?

[mmarchini]

v8-updates are running for node-test-commit-v8-linux, so this can be closed.

Ref: #1344 and #1344 (comment)