Fix for clone using deploy key spec

What does this MR do?

Fixing quarantined test clone_using_deploy_key_spec.rb per issue #196047 (closed) The error shown in issue shows that when trying to add the ssh key, something is wrong with the key results in Error loading key "(stdin)": invalid format There seems to be latency between UI action of adding the CiVariable and the data actually gets to the API. Solution is to add this variable using the API to avoid this latency.

Conformity

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Security

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