In the etymology you posted, Yiddish shadkhn is a loan from New Hebrew ShDKh 'match-maker, go-between' which is ultimately from Aramaic-Syriac. Schatz, OTOH, is a German word meaning 'treasure' (treasure is oytser in Yiddish) which is common in the Germanic languages and from a PIE root.

This is not to say of course that a Jewish match-maker couldn't associate the two words.