Remove "SimilarIssues" Bot prototype (#17598)

Removes the GitHub action that provides the functionality for the
similar issues bot prototype. We can onboard to the more official
prototype instead to conserve functionality.

.github/workflows/similarIssues.yml

@@ -1,33 +0,0 @@
-name: GitGudSimilarIssues comments
-
-on:
-  issues:
-    types: [opened]
-
-jobs:
-  getSimilarIssues:
-    runs-on: ubuntu-latest
-    outputs:
-      message: ${{ steps.getBody.outputs.message }}
-    steps:
-      - id: getBody
-        uses: craigloewen-msft/GitGudSimilarIssues@main
-        with:
-          issueTitle: ${{ github.event.issue.title }}
-          issueBody: ${{ github.event.issue.body }}
-          repo: ${{ github.repository }}
-          similaritytolerance: "0.8"
-  add-comment:
-    needs: getSimilarIssues
-    runs-on: ubuntu-latest
-    permissions:
-      issues: write
-    if: needs.getSimilarIssues.outputs.message != ''
-    steps:
-      - name: Add comment
-        run: gh issue comment "$NUMBER" --repo "$REPO" --body "$BODY"
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          NUMBER: ${{ github.event.issue.number }}
-          REPO: ${{ github.repository }}
-          BODY: ${{ needs.getSimilarIssues.outputs.message }}