[question] VirtualBuildEnv in packages that were not just built

### What is your question?

Hello!
At least when using conan 1 `VirtualBuildEnv(self)` does not seem to contain definitions from tool(or build) dependencies if the package was not built in the conan invocation.
The use case here is that we are doing some stuff in the `deploy()` method like setting up RPATHs, signing binaries etc. that would need dependencies given in the build-profile as tool requirements. But when the package to be deployed was not built in the same conan invocation the tool requirements do not show up in `self.dependencies` and hence they do not propagate any settings in `VirtualBuildEnv`. The only things we get there are variables from the `[buildenv]` section of the profile.
Is this intended behaviour and is it still present in conan2? I get it is an optimization to not instantiate build-context dependencies if not necessary but the behviour right now seems strange... - like a bug to be honest.

### Have you read the CONTRIBUTING guide?

- [x] I've read the CONTRIBUTING guide