Update fivem

[QuintenQVD0]

Update fivem as they removed their changelog page. Everything is now done just with grep on there download page

Description

• remove the DOWNLOAD_URL variable as now the FIVEM_VERSION variable accepts versions
• rewrite the get download URL script as their changelog page is offline
• update the description of the fivem version variable to set the example version to a valid one
• add the install finished echo that is also used in the steamcmd script

closes #2058

Checklist for all submissions

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you tested and reviewed your changes with confidence that everything works?
• Did you branch your changes and PR from that branch and not from your master branch?
  • If not, why?:

[KartoniarzEssa]

Working

[gOOvER]

Server is downloaded and TxAdmin start the server