Extend an Import script with additional options

To run a test import on staging, for measuring its efficiency, we need to perform a cleanup of the Imported project.
To do that, we need to add an option into the original Import script and refactor the flow, so we'll not exit immediately in case of the import failure.

The additional options are defaulted to false, so they should not affect the current usage of the script.

I consider making a separate job similar to (https://gitlab.com/alipniagov/performance/-/blob/master/.gitlab/ci/gpt-import-benchmark.yml) and create a scheduled pipeline which would only run over $TEST_TYPE == "Import benchmark" and will have a token of a staging user.