Use version-agnostic tags in Sitecore XM Cloud Docker Setup

It is now well-known that one of the main uses of moving Sitecore XM to XM Cloud is: developers don't need to be bothered about version upgrades. With that in mind, I raised this PR in May to replace 10.2-based version tag to ltsc tag and this was approved. Although this is trivial, since Sitecore developers are accustomed to version upgrades either on-premise or Sitecore managed cloud, now one of the main tenets with XMC is version-agnosticism. So, in case if you are working on XMC projects, ensure that version-agnostic numbers are used to reduce confusion:

Approved PR