workflows/pr: retry for 422 in prepare (#456980)

        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0

        with:

          retries: 3

          # The default for this includes code 422, which happens regularly for us when comparing commits:

          #   422 - Server Error: Sorry, this diff is taking too long to generate.

          # Listing all other values from here to effectively remove 422:

          #   https://github.com/octokit/plugin-retry.js/blob/9a2443746c350b3beedec35cf26e197ea318a261/src/index.ts#L14

          retry-exempt-status-codes: 400,401,403,404

          script: |

            require('./ci/github-script/prepare.js')({

              github,