Upgrade from net7.0 to LTS (or STS) image tag

[github-actions]

The following Dockerfile(s) target a .NET version that's no longer supported.
This is an auto-generated issue, detailed and discussed in dotnet/docs#22271.

Target version	End of life	Release notes	Nearest LTS TFM version
net7.0	May, 14 2024	net7.0 release notes	net8.0

• core/workers/background-service/Dockerfile
• core/workers/background-service/Dockerfile
• core/workers/background-service/Dockerfile
• core/workers/background-service/Dockerfile
• core/workers/cloud-service/Dockerfile
• core/workers/cloud-service/Dockerfile
• core/workers/cloud-service/Dockerfile
• core/workers/cloud-service/Dockerfile

Consider upgrading Dockerfile images to either the Standard Term Support (STS) or Long Term Support (LTS) versions.

If any of these Dockerfile(s) listed in this issue are intentionally targeting an unsupported version,
you can optionally configure to ignore these results in future automation executions.
Create a (or update the) dotnet-versionsweeper.json file at the root of the repository and
add an ignore entry following the
globbing patterns detailed here.

{
    "ignore": [
        "**/path/to/Dockerfile"
    ]
}