cookiecutter-event-application: Minor bug fixes

This MR includes the following minor bug fixes for the event application cookiecutter template:

1. The current example command passes cookiecutter-event-pipeline instead of cookiecutter-event-application as directory which causes cookiecutter to error out with:

A valid repository for "git+https://gitlab.wikimedia.org/repos/data-engineering/eventutilities-python.git"
could not be found in the following locations:
~/.cookiecutters/eventutilities-python/cookiecutter-event-pipeline

2. tmp_path, a function scoped fixture, is requested by some session scoped fixtures. As their lifetimes would mismatch, this causes pytest to raise:

ScopeMismatch: You tried to access the 'function' scoped fixture 'tmp_path' with a 'session' scoped request 
object, involved factories
conftest.py:24:  def fixture_sink_path(tmp_path)

This is fixed by requesting tmp_path_factory instead, which is session scoped.