Remove merge-dependabot (apache#3991)

This change removes the `merge-dependabot` workflow, which is no longer
useful in case of grouped upgrades.

Author: ppkarwasz

.github/workflows/build.yaml

@@ -29,7 +29,6 @@ permissions: read-all
 jobs:
 
   build:
-    if: github.actor != 'dependabot[bot]'
     uses: apache/logging-parent/.github/workflows/build-reusable.yaml@rel/12.1.1
     secrets:
       DV_ACCESS_TOKEN: ${{ startsWith(github.ref_name, 'release/') && '' || secrets.GE_ACCESS_TOKEN }}