[#68989754] Use vcloud-login for integration tests

Writes a temporary FOG_RC containing the API host and username which is used
by both vcloud-login and the integration tests.

This re-instates 5ebf8aa but without the typo that was corrected in a045304.
It was reverted because the token was echoed to STDOUT and logged by
Jenkins. I'll address this in a separate commit.

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Prevent token from being logged by Jenkins

Disable `set -x` in all Jenkins scripts so that the FOG_VCLOUD_TOKEN
environment variable is never logged by Jenkins. These scripts are fairly
simple so we shouldn't lose much by disabling bash debugging.

And explicitly disable debugging with `set +x` just before we set the token,
to guard against the possibility of someone unwittingly re-enabling this in
the future.