Merge pull request #44109 from cblecker/swagger-hack-fix

Automatic merge from submit-queue (batch tested with PRs 44104, 43903, 44109)

Update gen_api_ref_docs to use same diff method as verify

**What this PR does / why we need it**:
Fixes an issue where there is a discrepancy between the update and verify diff methods for the api-reference-docs. This can create a situation where verify will see changes, but update won't fix them.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #31129

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```

hack/lib/swagger.sh

@@ -130,17 +130,10 @@ kube::swagger::gen_api_ref_docs() {
   while read file; do
     if [[ -e "${output_dir}/${file}" && -e "${output_tmp}/${file}" ]]; then
       echo "comparing ${output_dir}/${file} with ${output_tmp}/${file}"
-      # Filter all munges from original content.
-      original=$(cat "${output_dir}/${file}")
-      generated=$(cat "${output_tmp}/${file}")
-
-      # Filter out meaningless lines with timestamps
-      original=$(echo "${original}" | grep -v "Last updated" || :)
-      generated=$(echo "${generated}" | grep -v "Last updated" || :)
 
       # By now, the contents should be normalized and stripped of any
       # auto-managed content.
-      if diff -B >/dev/null <(echo "${original}") <(echo "${generated}"); then
+      if diff -NauprB -I 'Last update' "${output_dir}/${file}" "${output_tmp}/${file}" >/dev/null; then
         # actual contents same, overwrite generated with original.
         cp "${output_dir}/${file}" "${output_tmp}/${file}"
       fi