Fix and simplify logic for setting the minimum VS version to display in the installer UI (#44412)

Author: marcpopMSFT

eng/Versions.props

@@ -193,10 +193,13 @@
          from the 'minimumMSBuildVersion' file in non-source-only cases into MicrosoftBuildMinimumVersion,
          then use that in Directory.Packages.props.
 
-         At usage sites, either we use MicrosoftBuildMinimumVersion, or MicrosoftBuildVersion in source-only modes. -->
+         At usage sites, either we use MicrosoftBuildMinimumVersion, or MicrosoftBuildVersion in source-only modes.
+
+         Additionally, set the MinimumVSVersion for the installer UI that's required for targeting NetCurrent -->
     <MicrosoftBuildVersion>17.12.7</MicrosoftBuildVersion>
     <MicrosoftBuildLocalizationVersion>17.12.7-preview-24522-03</MicrosoftBuildLocalizationVersion>
     <MicrosoftBuildMinimumVersion Condition="'$(DotNetBuildSourceOnly)' != 'true'">17.11.4</MicrosoftBuildMinimumVersion>
+    <MinimumVSVersion>17.12</MinimumVSVersion>
   </PropertyGroup>
   <PropertyGroup>
     <!-- Dependencies from https://github.com/dotnet/templating -->

src/Installer/redist-installer/targets/GenerateMSIs.targets

@@ -285,24 +285,6 @@
                       Overwrite="true" />
   </Target>
 
-  <Target Name="GetMinimumVSVersion"
-          BeforeTargets="GenerateSdkBundle"
-          Condition=" '$(OS)' == 'Windows_NT' "
-          Outputs="$(MinimumVSVersion)">
-    <PropertyGroup>
-      <MinimumMSBuildVersionFile Condition="$([System.Text.RegularExpressions.Regex]::Match(%(SDKInternalFiles.Identity),'.*minimumMSBuildVersion').Success) ">%(SDKInternalFiles.Identity)</MinimumMSBuildVersionFile>
-    </PropertyGroup>
-
-    <ReadLinesFromFile File="$(MinimumMSBuildVersionFile)">
-      <Output TaskParameter="Lines" PropertyName="MinimumVSVersion" />
-    </ReadLinesFromFile>
-
-    <PropertyGroup Condition=" '$(VersionSDKMinor)' == '1' and '$(StabilizePackageVersion)' == 'true' ">
-      <MinimumVSVersion>$(MinimumVSVersion.Substring(0,$(MinimumVSVersion.LastIndexOf('.'))))</MinimumVSVersion>
-      <MinimumVSVersion >$([MSBuild]::Add($(MinimumVSVersion), .1))</MinimumVSVersion>
-    </PropertyGroup>
-  </Target>
-
   <Target Name="GenerateSdkBundle"
           DependsOnTargets="GenerateLayout;AcquireWix;MsiTargetsSetupInputOutputs;GenerateSdkMsi;GenerateTemplatesMsis;GenerateWorkloadManifestsWxs"
           Condition=" '$(OS)' == 'Windows_NT' "