build(client): Remove LTS trigger in Build - client packages (microsoft#25966)

#### Description

LTS branch has been failing Real Service Stress Test pipeline since
September 14th, thus disabling the LTS trigger from the `Build - client
packages` until fix is applied.


#### Related PR

[Disable LTS Schedule
Run](https://github.com/microsoft/FluidFramework/compare/lts...test/lts-remove-schedule?expand=1)

Author: jikim-msft

tools/pipelines/test-real-service-stress.yml

@@ -18,7 +18,6 @@ resources:
       - release/*
       - main
       - next
-      - lts
   repositories:
   - repository: ff_pipeline_host
     type: git