Update vcloud-core for vcloud-login utility

Makes the new `vcloud-login` utility available and deprecates the use of
plaintext passwords in FOG_RC. Documentation about credentials is now
centralised.
Merge pull request #55 from gds-operations/update_core_vcloud_login

[#68989754] Update vcloud-core for vcloud-login utility
Consolidate jenkins test scripts

There was a lot of duplication between these scripts. Whereas the only
differences were us not doing the following in
`jenkins_integration_tests.sh` which is run against Carrenza:

- Not running unit tests. Which are fast and we wouldn't want to run the
  integration tests if they do fail.
- Publishing the gem. Which I've left in the original `jenkins.sh`.

We can later change the Carrenza job to run `jenkins_tests.sh` directly and
delete `jenkins_integration_tests.sh`.
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.
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.
Merge pull request #56 from gds-operations/vcloud_login_tests

[#68989754 #72170126] Use vcloud-login for tests
Remove redundant jenkins_integration_tests.sh

CI jobs for Carrenza have been changed to use `jenkins_tests.sh` directly:

https://github.gds/gds/jenkins-config-ci-new/compare/d8cfee63e9b8caea85e4a0fd866168a4c45fc216...f2ee83a439628830a37d8b542d5333596f73875b

Excuse the other changes in that diff. It seems that Jenkins doesn't persist
changes with "apply" so they include other changes since the jobs were last
"saved".
Merge pull request #57 from gds-operations/72170126-remove_jenkins_integration_tests

[#72170126] Remove redundant jenkins_integration_tests.sh
Refactor Launch to validate in .new, not .run.

Better to do set up and validation when the class is loaded, rather than defer it to when we want to get work done.