[6.0] Disable STJ build for 6.0.25 (#93761)

* [6.0] Disable STJ build for 6.0.25

* Turn on building MWC in this release, it was missed when we enabled STJ.

* Revert MWC change

Co-authored-by: Eric StJohn <[email protected]>

---------

Co-authored-by: Eric StJohn <[email protected]>

Author: carlossanlop

src/libraries/System.Text.Json/src/System.Text.Json.csproj

@@ -9,7 +9,7 @@
     <Nullable>enable</Nullable>
     <IncludeInternalObsoleteAttribute>true</IncludeInternalObsoleteAttribute>
     <IsPackable>true</IsPackable>
-    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
     <ServicingVersion>9</ServicingVersion>
     <PackageDescription>Provides high-performance and low-allocating types that serialize objects to JavaScript Object Notation (JSON) text and deserialize JSON text to objects, with UTF-8 support built-in. Also provides types to read and write JSON text encoded as UTF-8, and to create an in-memory document object model (DOM), that is read-only, for random access of the JSON elements within a structured view of the data.