Remove chained uses of TrimEnd and replace with char arrays / substring (#33977)

Author: ericstj

Directory.Build.props

@@ -358,9 +358,9 @@
     <TestPath Condition="'$(TestPath)' == ''">$(TestWorkingDir)$(MSBuildProjectName)/$(BuildConfiguration)/</TestPath>
     <RefRootPath>$(BinDir)ref/</RefRootPath>
     <BuildConfigurationRefPath>$(RefRootPath)$(_bc_TargetGroup)/</BuildConfigurationRefPath>
-    <BuildConfigurationRefPath Condition="$(_bc_TargetGroup.EndsWith('aot'))">$(RefRootPath)$(_bc_TargetGroup.TrimEnd('t').TrimEnd('o').TrimEnd('a'))/</BuildConfigurationRefPath>
+    <BuildConfigurationRefPath Condition="$(_bc_TargetGroup.EndsWith('aot'))">$(RefRootPath)$(_bc_TargetGroup.TrimEnd('aot'))/</BuildConfigurationRefPath>
     <RefPath>$(RefRootPath)$(TargetGroup)/</RefPath>
-    <RefPath Condition="$(TargetGroup.EndsWith('aot'))">$(RefRootPath)$(TargetGroup.TrimEnd('t').TrimEnd('o').TrimEnd('a'))/</RefPath>
+    <RefPath Condition="$(TargetGroup.EndsWith('aot'))">$(RefRootPath)$(TargetGroup.TrimEnd('aot'))/</RefPath>
     <NetStandardRefPath>$(RefRootPath)netstandard/</NetStandardRefPath>
     <NetFxRefPath>$(RefRootPath)netfx/</NetFxRefPath>
     <GlobalToolsDir>$([MSBuild]::NormalizeDirectory('$(ArtifactsDir)', 'tools'))</GlobalToolsDir>

external/docs/docs.depproj

@@ -17,7 +17,7 @@
       <DocFile Include="$(XmlDocFileRoot)/**/*.xml"/>
       <DocFile>
         <!-- trim off slash since it differs by platform and we need to do a string compare -->
-        <LCID>$([System.String]::new('%(RecursiveDir)').TrimEnd('\').TrimEnd('/'))</LCID>
+        <LCID>$([System.String]::new('%(RecursiveDir)').TrimEnd('\/'))</LCID>
         <!-- set metadata expected by depProj -->
         <NuGetPackageId>$(XmlDocPackage)</NuGetPackageId>
         <NuGetPackageVersion>$(XmlDocPackageVersion)</NuGetPackageVersion>