Don't overbuild when the ProjectToBuild / -projects flag is passed in (dotnet#59170)

* Create binlog when running project template tests

* Don't pass ProjectToBuild to both desktop msbuild and dotnet build when using both engines

* Don't build native tests in project templates

* revert these two

Author: ViktorHofer

.azure/pipelines/ci-public.yml

@@ -665,6 +665,7 @@ stages:
                   -NoBuild
                   -NoBuildDeps
                   -configuration Release
+                  -bl
           displayName: Run project template tests
 
         artifacts:

eng/build.ps1

@@ -293,7 +293,13 @@ if ($RuntimeSourceFeed -or $RuntimeSourceFeedKey) {
 [string[]]$MSBuildOnlyArguments = ''
 
 if ($All) { $dotnetBuildArguments += '/p:BuildAllProjects=true' }
-if ($Projects) { $MSBuildArguments += "/p:ProjectToBuild=$Projects" }
+if ($Projects) {
+    if ($BuildNative) {
+        $MSBuildOnlyArguments += "/p:ProjectToBuild=$Projects"
+    } else {
+        $dotnetBuildArguments += "/p:ProjectToBuild=$Projects"
+    }
+}
 
 if ($NoBuildInstallers) { $MSBuildOnlyArguments += "/p:BuildInstallers=false"; $BuildInstallers = $false }
 if ($BuildInstallers) { $MSBuildOnlyArguments += "/p:BuildInstallers=true" }