use existing token

Author: Artur-

.github/workflows/validation.yml

@@ -33,8 +33,8 @@ jobs:
     steps:
       - name: Check for required token
         run: |
-          if [ -z "${{ secrets.VAADIN_BOT_TOKEN }}" ]; then
-            echo "::error::VAADIN_BOT_TOKEN secret is required for formatter to trigger workflows after committing changes"
+          if [ -z "${{ secrets.GHTK }}" ]; then
+            echo "::error::GHTK secret is required for formatter to trigger workflows after committing changes"
             exit 1
           fi
 
@@ -43,7 +43,7 @@ jobs:
         with:
           ref: ${{ github.event.pull_request.head.ref }}
           repository: ${{ github.event.pull_request.head.repo.full_name }}
-          token: ${{ secrets.VAADIN_BOT_TOKEN }}
+          token: ${{ secrets.GHTK }}
           fetch-depth: 2
 
       - name: Check if last commit was from formatter bot