Correct ansible-test injector python behavior.
Correct ansible-test injector python behavior.

Inject a symlink to the correct python into the copied injector
directory instead of altering the shebang of the injector. This
has the side-effect of also intercepting `python` for integration
tests which simplifies cases where it needs to be directly invoked
without collecting code coverage.

thaim/ansible,thaim/ansible