Remove source-build workaround for sourcelink submodule issue (#39324)

Author: MichaelSimons

eng/SourceBuild.props

@@ -3,7 +3,6 @@
   <PropertyGroup>
     <GitHubRepositoryName>aspnetcore</GitHubRepositoryName>
     <SourceBuildManagedOnly>true</SourceBuildManagedOnly>
-    <CloneSubmodulesToInnerSourceBuildRepo>false</CloneSubmodulesToInnerSourceBuildRepo>
   </PropertyGroup>
 
   <Target Name="PrepareGlobalJsonForSourceBuild"
@@ -14,19 +13,6 @@
       WorkingDirectory="$(InnerSourceBuildRepoRoot)" />
   </Target>
 
-  <!--
-    Init submodules - temporarary workaround for https://github.com/dotnet/sourcelink/pull/653
-  -->
-  <Target Name="InitSubmodules"
-          DependsOnTargets="PrepareInnerSourceBuildRepoRoot"
-          BeforeTargets="RunInnerSourceBuildCommand">
-
-    <Exec
-      Command="git submodule update --init --recursive"
-      WorkingDirectory="$(InnerSourceBuildRepoRoot)"
-      EnvironmentVariables="@(InnerBuildEnv)" />
-  </Target>
-
   <!--
     Remove inner source .globalconfig file as both the inner and outer config files get loaded and cause a conflict.
     Leaving the inner will cause all conflicting settings to be ignored.