TLSYNTH-66 return messages from schedules service

MANDATORY

• Fill in the JIRA ticket using the following template :
• Merge or rebase the current branch with sprint (example : git rebase -i 3.11/sprint)
• Test the merged version (all unit tests / manual tests only for the issue)
• If needed, add or update Confluence documentation (except for bug fixes) https://moviplus.atlassian.net/wiki/spaces/SYN/pages/380895475/tdg+service+DisplayScreenContentFunction
• If needed, update the next release page : https://moviplus.atlassian.net/wiki/spaces/SYN/pages/287342640/Prochaine+version

Closes TLSYNTH-66