Revert "Merge pull request kcp-dev#43 from xrstf/fork-gentype"

This reverts commit 91bd851, reversing
changes made to 5ae6774.

Except for the .prow.yaml, which is a required upgrade in all branches.

Author: xrstf

.prow.yaml

@@ -7,7 +7,7 @@ presubmits:
       preset-goproxy: "true"
     spec:
       containers:
-        - image: ghcr.io/kcp-dev/infra/build:1.23.7-2
+        - image: ghcr.io/kcp-dev/infra/build:1.23.4-1
           command:
             - make
             - verify
@@ -20,7 +20,7 @@ presubmits:
       preset-goproxy: "true"
     spec:
       containers:
-        - image: ghcr.io/kcp-dev/infra/build:1.23.7-2
+        - image: ghcr.io/kcp-dev/infra/build:1.23.4-1
           command:
             - make
             - lint