[release pipeline] OfficialBuildId is incorrectly included in JSON of release announcement for 8.0 and 9.0

[mthalman]

The JSON snippet that is included with SB release announcements is including the OfficialBuildId field with an empty value for 8.0 and 9.0. This should only be included for 10.0 and above.

Example of what's being output:

{
  "Channel": "8.0",
  "Runtime": "8.0.16",
  "Sdk": "8.0.116",
  "TagUrl": "https://github.com/dotnet/dotnet/releases/tag/v8.0.16"
  "OfficialBuildId": ""
}

[ellahathaway]

This is being completed as part of my work for dotnet/dotnet#1116

[ellahathaway]

PR: https://dev.azure.com/dnceng/internal/_git/dotnet-release/pullrequest/51571

[ellahathaway]

PR merged, closing