Merged PR 42841: [internal/release/8.0.3xx] - Updated SourceBuildPrebuiltBaseline.xml

Updated SourceBuildPrebuiltBaseline.xml - add prebuilt
System.Reflection.Metadata 8.0.0

----
#### AI description  (iteration 1)
#### PR Classification
Code update for release preparation.

#### PR Summary
Updated the `SourceBuildPrebuiltBaseline.xml` to include a new usage pattern for the upcoming release.
- `eng/SourceBuildPrebuiltBaseline.xml`: Added `System.Reflection.Metadata/*8.0.0*` to the ignore patterns.

Author: vseanreesermsft

eng/SourceBuildPrebuiltBaseline.xml

@@ -43,6 +43,7 @@
     <UsagePattern IdentityGlob="Microsoft.TemplateEngine.Utils/8.0.*" />
     <UsagePattern IdentityGlob="Microsoft.TemplateSearch.Common/8.0.*" />
     <UsagePattern IdentityGlob="System.Drawing.Common/8.0.*" />
+    <UsagePattern IdentityGlob="System.Reflection.Metadata/*8.0.0*" />
     <UsagePattern IdentityGlob="System.Threading.Tasks.Dataflow/*8.0.0*" />
     <UsagePattern IdentityGlob="Valleysoft.DockerCredsProvider/*" />
   </IgnorePatterns>