.github/workflows: generalize GH workflow for adding apm:ecosystems l…

…abel (DataDog#2496)

.github/workflows/ecosystems-label.yml

@@ -1,18 +1,21 @@
 name: Label APM Ecosystems issues
 on:
  issues:
+ paths:
+ - "contrib/**"
  types:
  - reopened
  - opened
  - edited
  pull_request:
+ paths:
+ - "contrib/**"
  types:
  - opened
  - reopened
  - edited
 jobs:
  label_issues:
- if: contains(github.event.pull_request.title, 'contrib')
  runs-on: ubuntu-latest
  steps:
  # https://github.com/marketplace/actions/actions-ecosystem-add-labels