Allow GlobalizationMode.Invariant = false to be substituted by the trimmer. (#47999)

This allows a Blazor WASM app to trim unused Invariant code when Invariant mode isn't enabled.

Author: eerhardt

src/libraries/System.Private.CoreLib/src/ILLink/ILLink.Substitutions.Shared.xml

@@ -8,6 +8,7 @@
     </type>
     <type fullname="System.Globalization.GlobalizationMode">
       <method signature="System.Boolean get_Invariant()" body="stub" value="true" feature="System.Globalization.Invariant" featurevalue="true" />
+      <method signature="System.Boolean get_Invariant()" body="stub" value="false" feature="System.Globalization.Invariant" featurevalue="false" />
     </type>
     <type fullname="System.LocalAppContextSwitches">
       <method signature="System.Boolean get_EnableUnsafeUTF7Encoding()" body="stub" value="false" feature="System.Text.Encoding.EnableUnsafeUTF7Encoding" featurevalue="false" />