Adding CA certificate into Coder template failing build (k8s)

Using the [devcontainer Coder template](https://github.com/coder/coder/blob/main/examples/templates/kubernetes-devcontainer/main.tf) I'm seeing the following issue when mounting my CA certificates:

```bash
error: temp remount: temp remount: bind mount /ca-certs/ca-file => /.envbuilder/mnt/ca-certs/ca-file: permission denied
```

Adding certificate directory to ENV:
```hcl

locals {
...
"SSL_CERT_DIR" : "/ca-certs"
//or
"SSL_CERT_FILE": "/ca-certs/ca-file"
}
```

```hcl
resource "kubernetes_deployment" "main" {
...

spec {
template {
spec {
...
volume_mount {
name = "ca-file"
mount_path = "/ca-certs/ca-file"
}
}

volume {
name = "ca-file"
secret {
secret_name = "coder-tls"
}
...
}
}
```

Just trying to have the container built trust my private PKI services.

从 examples/templates/kubernetes-devcontainer/main.tf 开始，使用报告中的配置在 Kubernetes 中复现 CA 证书挂载。跟踪环境构建器对 /ca-certs/ca-file bind mount 的处理，并验证构建可以信任私有 PKI，且不会出现 permission-denied remount error。

由索引模型根据 Issue 内容生成。