Fix extra space in MSBuild variable that causes BuildingAnOfficialBuildLeg to be set incorrectly. (#29640)

Author: crummel

pkg/dir.props

@@ -6,7 +6,7 @@
     <!-- Used to determine if we should build some packages only once across multiple official build legs.
          For offline builds we still set OfficialBuildId but we need to build all the packages for a single
          leg only, so we also take DotNetBuildFromSource  into account. -->
-    <BuildingAnOfficialBuildLeg Condition="'$(BuildingAnOfficialBuildLeg)' == '' AND '$(OfficialBuildId)' != '' AND '$(DotNetBuildFromSource )' != 'true'">true</BuildingAnOfficialBuildLeg>
+    <BuildingAnOfficialBuildLeg Condition="'$(BuildingAnOfficialBuildLeg)' == '' AND '$(OfficialBuildId)' != '' AND '$(DotNetBuildFromSource)' != 'true'">true</BuildingAnOfficialBuildLeg>
   </PropertyGroup>
 
   <!-- Packages opt-in to automatic RID-specific builds by placing a *.RID.props next to their project