python: remove broken/ineffectual keywords marks initialization

By my analysis, this deleted code block has no effect:

1. `self.keywords` is `update`d with `callspec.marks`.
2. `self.own_markers` is `update`d with `callspec.marks`.
3. `self.keywords` is `update`d with `self.own_markers`.

So together steps 2+3 completely undo step 1.

Author: bluetech

src/_pytest/python.py

@@ -1662,13 +1662,6 @@ def __init__(
         self.own_markers.extend(get_unpacked_marks(self.obj))
         if callspec:
             self.callspec = callspec
-            # this is total hostile and a mess
-            # keywords are broken by design by now
-            # this will be redeemed later
-            for mark in callspec.marks:
-                # feel free to cry, this was broken for years before
-                # and keywords can't fix it per design
-                self.keywords[mark.name] = mark
             self.own_markers.extend(callspec.marks)
         if keywords:
             self.keywords.update(keywords)