GCP tests fixes

[denis256]

Noticed that GCP tests started to fail with errors like:

TestTerraformGcpInstanceGroupExample 2022-02-13T15:01:51Z retry.go:99: Returning due to fatal error: FatalError{Underlying: error while running command: exit status 1; ╷
│ Error: Error resolving image name 'ubuntu-os-cloud/ubuntu-1604-lts': Could not find image or family ubuntu-os-cloud/ubuntu-1604-lts

or

TestImportSSHKeyOSLogin 2022-02-13T20:14:34Z oslogin.go:101: Getting login profile for user [email protected]
    compute_test.go:205: Error launching new Compute Instance: googleapi: Error 400: Invalid value for field 'resource.machineType': 'zones/southamerica-west1-a/machineTypes/f1-micro'. Machine type with name 'f1-micro' does not exist in zone 'southamerica-west1-a'., invalid

Looks like ubuntu-1604 image is only in as "ubuntu-pro" with additional costs

https://user-images.githubusercontent.com/10694338/153772991-edb90b91-bcba-4c3e-9ee5-f969b4296ac2.png

Updated tests to use ubuntu-2004-lts image, removed region southamerica-west1 from tests since can't be deployed f1-micro instances there.

[yorinasub17]

LGTM!

[yorinasub17]

Merging so we can start to see these tests pass!