Can a non-tiefling with the Adopted and Prolong Magic traits extend their racial grant spell-like abilities?
Pure RAW: No. The trait specifies "spell-like abilities gained through your tiefling heritage". As such, it doesn't give any benefits to abilities gained from other races.
Non-RAW / Me as a lenient GM: Yes. We can make it work. The spell-like abilities of other races is typically not as powerful as some of the tiefling choices.
The difference is that they don't refer to the heritage in the effect of the trait.
The effect of Prolong Magic is specifically tied to the spell-like ability granted by the various Tiefling heritages.
But again, I would put too much weight on the RAW in that. I don't expect designers to have considered every possibility of using it on other races through adopted, and therefore formulated it to disallow that.
I wonder if it would apply to a tiefling who was reincarnated as another creature with spell-like abilities.
This could open up a new discussion, as I don't see spell-like abilities as something depending on the new form, thus not gained or lost through reincarnation..