What is the term that defines an adjective used solely to emphasize the noun with which it is associated? The adjective does not describe the noun - merely emphasizes it - as in "those ‘darned’ kids!"

An intensive or intensifier: "A word (adverbial or adjectival in function) which has a typically heightening effect on the meaning of another element in a sentence ..." (Crystal’s Dictionary of Language and Languages).
It’s usually applied to words like very, but the OED describes damned being used as "a mere intensive" in the sort of phrase you give.

Grant