Should I rack lager before pitching yeast?

If you brewed from extract, then it probably is mostly cold break possibly some hop material as well. Even if you chilled in the kettle, it takes time to settle and so it would have been racked along with the wort.

It's not essential, but should you choose to do so you can keep the trub out of the fermentor by whirlpooling the wort in the kettle and leaving it for 15-30 mins until you can see the trub on the bottom of the kettle. Then transfer from the kettle leaving the trub behind.

One problem with so much trub is that it throws off your volume in the fermentor. You think you've got 5.5 gallons - half a gallon for samples and losses in racking, to reach a 5 gallon batch, but later find that a fairly large chunk of that is trub - invisible until it settles out, leaving you with maybe only 5 gallons into primary, meaning you'll probably only get 4.5-4.75 packaged. Not a problem when bottling, but a bit of a waste of capacity when kegging. Keeping the trub out of the fermentor is a big step to getting accurate volume in the fermentor and hitting your intended batch size.

Tests at the homebrew level have shown that there is no benefit to racking off the trub. But it won't hurt, either, if you want to do it. So, the answer is, either way is fine. I'd be inclined to leave it based on the theory that the less you mess with the beer, the better off you are. In addition, I can't think of a major brewer that settles then racks off.