Remove user name from orchestrator run name

[schustmi]

Describe changes

When generating a run name which we use to display in the orchestrator UI, we previously included the user name. For ZenML cloud tenants, that user name is the email of the user, which contains an @ which leads to failure when running with Airflow.
To fix it, we simply remove the user name and increase the random portion of the run name.

Pre-requisites

Please ensure you have done the following:

• I have read the CONTRIBUTING.md document.
• If my change requires a change to docs, I have updated the documentation accordingly.
• If I have added an integration, I have updated the integrations table and the corresponding website section.
• I have added tests to cover my changes.
• I have based my new branch on develop and the open PR is targeting develop. If your branch wasn't based on develop read Contribution guide on rebasing branch to develop.

Types of changes

• 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 change)
• Other (add details above)

[htahir1]

If this is unique and works for all orchestrators then LGTM!

[bcdurak]

🦭