Remove applied source build patch

src/SourceBuild/tarball/patches/sdk/0001-Add-explicit-System.Text.Json-dependency.patch

@@ -1,31 +0,0 @@
-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: Nikola Milosavljevic <nikolam@microsoft.com>
-Date: Mon, 26 Jun 2023 23:02:20 +0000
-Subject: [PATCH] Add explicit System.Text.Json dependency
-
-Adding an excplicit System.Text.Json dependency to prevent transitive dependency to be picked up
-from PSB, via Microsoft.Build package.
-
-Backport: https://github.com/dotnet/sdk/pull/33618
----
- src/BuiltInTools/dotnet-watch/dotnet-watch.csproj | 7 +++++++
- 1 file changed, 7 insertions(+)
-
-diff --git a/src/BuiltInTools/dotnet-watch/dotnet-watch.csproj b/src/BuiltInTools/dotnet-watch/dotnet-watch.csproj
-index 065f750f72..13d2c1ed99 100644
---- a/src/BuiltInTools/dotnet-watch/dotnet-watch.csproj
-+++ b/src/BuiltInTools/dotnet-watch/dotnet-watch.csproj
-@@ -23,6 +23,13 @@
-     <PackageReference Include="Microsoft.Build.Locator" Version="$(MicrosoftBuildLocatorPackageVersion)" />
-     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Features" Version="$(MicrosoftCodeAnalysisCSharpFeaturesPackageVersion)" />
-     <PackageReference Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="$(MicrosoftCodeAnalysisWorkspacesMSBuildPackageVersion)" />
-+
-+    <!--
-+      Explicit System.Text.Json package reference is required for source-build to pick up the live package.
-+      Avoids picking up an old version via transitive dependency from Microsoft.Build or Microsoft.CodeAnalysis.Workspaces.MSBuild.
-+    -->
-+    <PackageReference Include="System.Text.Json" Version="$(SystemTextJsonVersion)" Condition="'$(DotnetBuildFromSource)' == 'true'" />
-+
-     <Compile Include="$(RepoRoot)src\Common\PathUtilities.cs" LinkBase="Common" />
-   </ItemGroup>
-