Unignore rustpkg test_no_rebuilding

[sfackler]

#10254 exposed an underlying issue with this test. It creates a crate, runs rustpkg test, sets the test binary to read only, and then reruns rustpkg test checking if it failed to compile. However, since the binary is read only, it fails to execute which now generates an error and a non-0 status code.

I've just disabled it.

[sfackler]

rustpkg doesn't exist anymore, closing