I don't have Inventor 2017 (you should install the Updates for 2017), so I will have to type out description of steps.
In assembly Shift Right Click and select Part Priority filter.
Right click on the sheet metal part and select Edit (not Open).
Start a new sketch on the face of the sheet metal part (or the XY Plane of the part).
Project Geometry a circular edge of the pipes.
You can offset circles for clearance and then Extrude-Cut.
Alternatively,
You could edit the part as above but then
Modify>Copy Object and copy face of pipes into sheet metal part to use to Split or Sculpt the holes.
With either of these techniques - if you move the pipes, the hole positions will automatically update.
Edit: I just noticed that you used the same sheet metal part on the other side.
This presents a problem.
I would Derive Component the sheet metal part and use the original un-cut on the one side and then the Derived Component on the side to be cut. Then as above.
-----------------------------------------------------------------------------------------
Autodesk Inventor 2019 Certified Professional
Autodesk AutoCAD 2013 Certified Professional
Certified SolidWorks Professional