Don't tell the user to add account_id after running `wrangler gener…

…ate`

Before, wrangler would give this message:
```
> wrangler generate
  Creating project called `worker`...
  Done! New project created /home/jnelson/src/test-project/worker/worker
  🕵️  You can find your zone_id in the right sidebar of a zone's overview tab at https://dash.cloudflare.com
  🕵️  You can copy your account_id below
  +----------------------------+----------------------------------+
  | Account Name               | Account ID                       |
  +----------------------------+----------------------------------+
  | Jyn514@gmail.com's Account | e1706d218241c1230155b4f91b3218af |
  +----------------------------+----------------------------------+
  🕵️  You will need to update the following fields in the created wrangler.toml file before continuing:
  - account_id
```

Adding the account ID is no longer necessary, so don't suggest adding it.

src/settings/toml/manifest.rs

@@ -414,9 +414,6 @@ impl Manifest {
         let account_id_env = env::var("CF_ACCOUNT_ID").is_ok();
         let zone_id_env = env::var("CF_ZONE_ID").is_ok();
         let mut top_level_fields: Vec<String> = Vec::new();
-        if !account_id_env {
-            top_level_fields.push("account_id".to_string());
-        }
         if let Some(kv_namespaces) = &self.kv_namespaces {
             for kv_namespace in kv_namespaces {
                 top_level_fields.push(format!(