Update devcontainer config, to remove /etc/os-release mount (#54897)

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### What does this PR do?

Remove /etc/os-release mount that breaks some dpkg interactions, like in `sudo unminimize`.
Also move `HOST_*` env variables so that they are propagated correctly to the ssh connection

### Motivation

### Describe how you validated your changes

### Additional Notes


Co-authored-by: nicolas.schweitzer <nicolas.schweitzer@datadoghq.com>

Author: KevinFairise2

.devcontainer/datadog/default/devcontainer.json

@@ -19,8 +19,6 @@
     "-v",
     "/:/host/root:ro",
     "-v",
-    "/sys/kernel/debug:/sys/kernel/debug",
-    "-v",
-    "/etc/os-release:/etc/os-release"
+    "/sys/kernel/debug:/sys/kernel/debug"
   ]
 }

.devcontainer/datadog/default/features/datadog-agent/install.sh

@@ -24,4 +24,7 @@ cp /var/config/dd/dd-agent-workspace-env.sh /etc/profile.d/50-agent-workspace-en
 # /etc/zsh/zshenv sources these files.
 cat > /etc/profile.d/zz-ddagent-workspace-env.sh << 'EOF'
 export PATH="/home/bits/.local/bin:$PATH" # Make sure we keep it in the path some useful tooling is there
+export HOST_ROOT="/host/root"
+export HOST_PROC="/host/root/proc"
+export HOST_SYS="/host/root/sys"
 EOF

.devcontainer/datadog/default/prebuild-devcontainer.json

@@ -26,10 +26,5 @@
         "IPC_LOCK",
         "CHOWN",
         "KILL"
-    ],
-    "containerEnv": {
-        "HOST_ROOT": "/host/root",
-        "HOST_PROC": "/host/root/proc",
-        "HOST_SYS": "/host/root/sys"
-    }
+    ]
 }