The question is not trivial, and to my knowledge the answer is not known: there is no known uniform upper bound for the $p$-adic valuation of $(p-1)!+1$ (although such a bound most probably exists, as you indicate).
The only result I know in this direction is that $(p-1)!+1$ is not a power of $p$ for any $p>5$, see e.g. this link. EDIT. I have in my notes that this result is due to Liouville, but I cannot find the precise reference.
This does provide an upper bound for the $p$-adic valuation, although a very weak one. A natural problem would be to improve this bound, but a uniform upper bound may be out of reach given current technology.