Revert "Provide default value for haxe::target"

This reverts commit d4a8174bb1760403d496b4e5f03dcb5ab5c9d1a6.
Revert "Allow initialize csharp:haxe::target before haxeCSharpSettings"

This reverts commit 8bf1a7dfdcebb52b00fbb271e2b62ccda0231729.