Revert "Require the workload for wasm threading (#98498)"

This reverts commit 3848f56.

Author: maraf

src/mono/nuget/Microsoft.NET.Workload.Mono.Toolchain.Current.Manifest/WorkloadManifest.targets.in

@@ -54,7 +54,6 @@
     <!-- $(WasmBuildNative)==true is needed to enable workloads, when using native references, without AOT -->
     <!-- FIXME: is the blazor condition here correct? -->
     <_WasmNativeWorkloadNeeded Condition="
-        '$(WasmEnableThreads)' == 'true' or
         '$(_WasmPropertiesDifferFromRuntimePackThusNativeBuildNeeded)' == 'true' or
         '$(RunAOTCompilation)' == 'true' or
         '$(WasmBuildNative)' == 'true' or