Attaching wood railing to cement

I would use a Diamond Grinding wheel and grind the concrete around the pipe till it is level. Probably take less than an hour at each corner.
Once concrete is level, use metal grinding wheel to cut the pipe level.
I used a similar diamond wheel on my sidewalk, and remove a raised 3/8 corner – 15 inches on each side of the raised corner in about 3-4 hours.

Once level, just use a standard 4x4 bracket to mount the wood post. You can use the hole in the pipe to anchor the bolt for the braket. Fill with 6" of epoxy and insert bolt and bracket.

As explained in my linked answer, I cut a half-lap joint into the 4x4 post. I set the post on top of the step with the lap hanging over, then drilled holes and drove sleeve anchors through the wood and into the concrete.

Here is a highly non-technical Paint sketch of what I'm talking about. On the left is the view looking toward your door (essentially the view of the picture you shared), on the right is the view from the right, looking at the steps. Grey is the concrete step, brown is the wooden post, red represents the sleeve anchor.

You would want to be sure the post is sitting on a level spot of concrete. Either grind the concrete flat right at the corner of the top step or move the post in, away from the bulge around the current pipes.

To avoid having to deal with the mound of concrete entirely, and to avoid cutting the 4x4 post, you could put the entire 4x4 post on the "outside" of the steps, like this:

I used 6" anchors for my half-lap solution with roughly 2" through the wood and 4" into the concrete (I actually bought 7" bolts because that's all they had in stock that day). If you go with the full 4x4 on the side, you'll want to use anchors at least 8" so you have 4" through wood and 4" into the concrete.

Put one post at each end, put a railing (plain and simple or fancy and decorative) between them and Bob's your uncle!