chore: Remove check-legacy-links-format workflow (#3376)

This workflow has been deprecated in favor of similar checks in other places.

.github/workflows/check-legacy-links-format.yml

@@ -1,22 +0,0 @@
-name: Legacy Link Format Checker
-
-on:
-  push:
-    paths:
-      - "website/content/**/*.mdx"
-      - "website/data/*-nav-data.json"
-      - ".github/workflows/check-legacy-links-format.yml"
-
-permissions:
-  contents: read
-
-jobs:
-  check-links:
-    if: github.repository == 'hashicorp/boundary'
-    uses: hashicorp/dev-portal/.github/workflows/docs-content-check-legacy-links-format.yml@475289345d312552b745224b46895f51cc5fc490
-    with:
-      repo-owner: "hashicorp"
-      repo-name: "boundary"
-      commit-sha: ${{ github.sha }}
-      mdx-directory: "website/content"
-      nav-data-directory: "website/data"