fix: Fix unit tests

[fnesveda]

The CLI unit tests were not running correctly for a while.

The problem was:

• some tests were configured to be skipped when the ~/.apify directory exists (meaing somebody is already logged in with apify login)
• but before each command, the checkLatestVersion method was called, which writes the latest version to ~/.apify/state.json
• this caused all of the tests which checked for ~/.apify existence to be skipped

I fixed it so that:

• the checkLatestVersion is skipped when the APIFY_CLI_SKIP_UPDATE_CHECK environment variable is set
• the tests are called with APIFY_CLI_SKIP_UPDATE_CHECK=1
• the tests actually fail if the ~/.apify directory exists at their start (so that we notice these issues immediately next time)
• the after() hook is skipped if the before() hook throws an error (this was causing some chdirs to be called when they shouldn't be)

Fixing the test execution revealed some errors in the push test, so I fixed those too - I mostly deleted some tests which didn't really make sense.

I also fixed the tests to clean up the created actors on the platform.

Closes #369.