Wait on deployment to demo environment before running e2e

[mendaomn]

Description

This PR introduces a dependency between the demo_deploy workflow and the e2e_tests workflow

Changes

• use workflow_run as trigger to e2e_tests workflow
• only run the jobs on success

How Has This Been Tested?

I haven't

PR Quality Checklist

• [ ] I added tests to new or existing code
• [ ] I removed hardcoded strings and used our i18n solution instead (see here)
• [ ] I made sure no sensitive info gets logged at any time in the codebase (see here) (e.g. no user info or details, no stacktraces, etc.)
• [ ] I checked that infrastructure/update_infrastructure.sh runs without any error
• [ ] I checked that npm run build builds without any error
• [ ] I checked that clusters are listed correctly
• [ ] I checked that a new cluster can be created (config is produced and dry run passes)
• [ ] I checked that login and logout work as expected

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