Don't depend on source-build job while it isn't running (dotnet#46220)

Author: wtgodbe

.azure/pipelines/ci.yml

@@ -831,7 +831,6 @@ stages:
                 - MacOS_Test
                 - Linux_Test
                 - Helix_x64
-            - Source_Build_Managed
           pool:
             name: NetCore1ESPool-Internal
             demands: ImageOverride -equals 1es-windows-2019
@@ -870,7 +869,6 @@ stages:
                 - MacOS_Test
                 - Linux_Test
                 - Helix_x64
-            - Source_Build_Managed
           pool:
             name: NetCore1ESPool-Internal
             # Visual Studio Enterprise - no BuildTools agents exist internally and job must run on Windows