remove hack/tools

The logcheck tool was moved to https://github.com/kubernetes-sigs/logtools and
it seems unlikely that we'll want to add another, similar tool under hack/tools
again, so the entire directory gets removed.

.github/workflows/test.yml

@@ -18,8 +18,6 @@ jobs:
       run: |
         go get -t -v ./...
         go test -v -race ./...
-    - name: Test hack/tools
-      run: cd hack/tools && go test -v -race ./...
     - name: Test examples
       run: cd examples && go test -v -race ./...
   lint:

README.md

@@ -28,7 +28,6 @@ Historical context is available here:
 Semantic versioning is used in this repository. It contains several Go modules
 with different levels of stability:
 - `k8s.io/klog/v2` - stable API, `vX.Y.Z` tags
-- `k8s.io/hack/tools` - no stable API yet (may change eventually or get moved to separate repo), `hack/tools/v0.Y.Z` tags
 - `examples` - no stable API, no tags, no intention to ever stabilize
 
 Exempt from the API stability guarantee are items (packages, functions, etc.)