fix: gitlab vars

[kasemAlem]

Fix error message when Gitlab env variables are empty to meet
the changed Gitlab variables as in constants.

Issue ticket number and link

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added meaningful description with JIRA/GitHub issue key(if applicable), for example HASSuiteDescribe("STONE-123456789 devfile source")
• I have updated labels (if needed)

[tisutisu]

/lgtm

[dheerajodha]

/lgtm

[dheerajodha]

thanks for this PR, this confused me a lot of times

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dheerajodha, psturc

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