Adding a timer to delay ui server startup

[gwenall]

Checklist:

• [ ] The code follows our code conventions.
• [ ] Important principle changes have been documented in the wiki.
• [ ] The new code is covered by unit tests with assertions.
• [x] The behaviour node and UI have been manually tested and is as expected.
• [ ] The squash commit message follows our conventions.

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

0.0% Coverage
0.0% Duplication

[JeremyPansier]

work done within https://github.com/my-cloud/ruthenium/pull/186