chore: replace issue triaing actions with nissuer (#55525)

### What?

Moving maintenance to a separate repository.

### Why?

I want to make these actions reusable in other projects as they seem to work well in the Next.js repository.

### How?

The code is moved to https://github.com/balazsorban44/nissuer

I tested it on my fork, and all the following functionality is preserved: balazsorban44#56

- [x] Close/lock/comment without a valid reproduction link
- [x] Minimize "+1"
- [x] Add labels based on user selection
- [x] Add comment based on the maintainer's label (eg.: "please add a complete reproduction")

.eslintignore

@@ -20,7 +20,6 @@ packages/react-refresh-utils/**/*.js
 packages/react-dev-overlay/lib/**
 **/__tmp__/**
 .github/actions/next-stats-action/.work
-.github/actions/issue-validator/*/index.mjs
 .github/actions/validate-docs-links/lib/index.js
 .github/actions/needs-triage/index.js
 .github/actions/*/index.mjs