ci: remove disabled testground workflow

.github/workflows/testground-on-push.yml

@@ -1,38 +0,0 @@
----
-name: Testground PR Checker
-
-on:
-  workflow_dispatch:
-  push:
-
-
-jobs:
-  testground:
-    if: github.repository == 'ipfs/kubo' || github.event_name == 'workflow_dispatch'
-    runs-on: ubuntu-latest
-    name: ${{ matrix.composition_file }}
-    strategy:
-      matrix:
-        include:
-          - backend_addr: ci.testground.ipfs.team
-            backend_proto: https
-            plan_directory: testplans/bitswap
-            composition_file: testplans/bitswap/_compositions/small-k8s.toml
-          - backend_addr: ci.testground.ipfs.team
-            backend_proto: https
-            plan_directory: testplans/bitswap
-            composition_file: testplans/bitswap/_compositions/medium-k8s.toml
-          - backend_addr: ci.testground.ipfs.team
-            backend_proto: https
-            plan_directory: testplans/bitswap
-            composition_file: testplans/bitswap/_compositions/large-k8s.toml
-    steps:
-      - uses: actions/checkout@v2
-      - name: testground run
-        uses: testground/testground-github-action@v1
-        timeout-minutes: 5
-        with:
-          backend_addr: ${{ matrix.backend_addr }}
-          backend_proto: ${{ matrix.backend_proto }}
-          plan_directory: ${{ matrix.plan_directory }}
-          composition_file: ${{ matrix.composition_file }}