Make tracking call to real noop

[bitPogo]

Describe the bug
In the current implementation, all calls pushes still to window._paq even if the tracker is disabled.

To Reproduce
Steps to reproduce the behavior:

1. Create a instance of a tracker and set the disabled flag to true
2. Use pushInstruction() for instance one or multiple times
3. Inspect the window._paq

Expected behavior
The array should still be empty.

[andyjdavis]

Is there any value in having window._paq populated when testing Matomo integration into a React app?

[bitPogo]

Hey, the issue is already a bit aged and I am currently engaged in some other topics, so I just want to let you know that it might can take a short while until I can tell you why I saw there an issue. Hope this is okay.