Remove devcontainer since it does not work with start-keycloak

.devcontainer/devcontainer.json

@@ -1,23 +0,0 @@
-{
-    "name": "Keycloakify Starter Devcontainer",
-    "image": "mcr.microsoft.com/devcontainers/typescript-node:1-20-bookworm",
-    "features": {
-        "ghcr.io/devcontainers/features/docker-in-docker:2": {
-            "moby": true,
-            "installDockerBuildx": true,
-            "version": "latest",
-            "dockerDashComposeVersion": "none"
-        },
-        "ghcr.io/devcontainers-contrib/features/maven-sdkman:2": {
-            "version": "latest",
-            "jdkVersion": "latest",
-            "jdkDistro": "ms"
-        }
-    },
-    "postCreateCommand": "yarn install",
-    "customizations": {
-        "vscode": {
-            "extensions": ["dbaeumer.vscode-eslint", "esbenp.prettier-vscode"]
-        }
-    }
-}