Remove aspnetcore submodule workaround (#43775)

* Remove sourcelink workaround
* Use Fedora 33 for source-build leg
* Update source-build container to centos-stream8

.azure/pipelines/ci.yml

@@ -733,7 +733,7 @@ stages:
     parameters:
       platform:
         name: 'Managed'
-        container: 'mcr.microsoft.com/dotnet-buildtools/prereqs:centos-7-20210714125435-9b5bbc2'
+        container: 'mcr.microsoft.com/dotnet-buildtools/prereqs:centos-stream8-20220809204800-17a4aab'
         buildScript: './eng/build.sh $(_PublishArgs) --no-build-repo-tasks'
         skipPublishValidation: true
         timeoutInMinutes: 120

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.