Rm powershell feature (#1752)

Author: pamelafox

.devcontainer/devcontainer.json

@@ -7,7 +7,6 @@
             "version": "18",
             "nodeGypDependencies": false
         },
-        "ghcr.io/devcontainers/features/powershell:1.1.0": {},
         "ghcr.io/devcontainers/features/azure-cli:1.0.8": {},
         "ghcr.io/azure/azure-dev/azd:latest": {}
     },