Does violating the Istikhara after feeling a constriction in one's chest incur Allah's wrath?

What you did by proceeding to work in that job is the most probable outcome for someone who has sought guidance (through Istikhara), for what Allah has decreed for you is good. You must accustom yourself to being content with Allah's decree, for divine choice is better than a servant's choice for himself. Istikhara is recommended (mustahabb) and not obligatory (wajib), and abandoning it or not acting upon its outcome does not incur Allah's displeasure, but it causes the servant to miss out on what is more befitting for him.