Add external_vault and vault_url to jx-boot-job-env-vars secret

[ankitm123]

Summary

For external vault, end users have to manually set EXTERNAL_VAULT = true and VAULT_URL = in the version stream makefile.

The issue with this is that every time they run jx gitops upgrade, the make file will get over written.

What we can do instead is set those values in the jx-boot-job-env-vars secret in the jx-git-operator namespace