* Revert "Fix error when there are no config files"

This reverts commit 32edfff7aae15654d2cfa4a10da9b8f81e021bce.

* Fix upgrader with specified ESLint config

Upgrader improperly kept detecting ESLint config file when engine had
a specific config file specified.

This behaviour resulted in providing upgrade instructions for the wrong
config file or in worse case trowing an exception of missing config
file.