Run integration tests for tf 0.14+

[melinath]

#313 added support for running integration tests in CI for multiple TF versions; however, TF 0.14+ can't run against the TF plan files (which are from 0.12). Ideally we would be able to run the integration tests against all supported TF versions.

[melinath]

Perhaps there's a script for automatically updating the plan files that we could use? I think there was a major update in 0.13 so we might just need to do this once, instead of once per version.

[melinath]

b/211885549