Remove ParallelCluster API docker logic

When working on ParallelCluster Lambda Layer, we changed the Pcluster API Lambda function from "Lambda+Docker" to "Lambda default runtime" aws#4845.

Therefore, we no long use any ECR images for pcluster API. The code and release process should be removed accordingly.

Signed-off-by: Hanwen <[email protected]>

Author: hanwen-cluster

.github/workflows/ci.yml

@@ -209,13 +209,6 @@ jobs:
       - name: Verify External SlurmDBD Template
         run:
           git diff --exit-code --quiet cloudformation/external-slurmdbd/external-slurmdbd.json cloudformation/external-slurmdbd/cdk.out/ExternalSlurmdbdStack.template.json
-  api-docker-test:
-    name: API Docker Tests
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: mikefarah/[email protected]
-      - run: api/docker/awslambda/docker-build.sh
   shellcheck:
     name: Shellcheck
     runs-on: ubuntu-latest