🐛 BUG: `service` should be an optional field under `[[services]]`

### Which Cloudflare product(s) does this pertain to?

Wrangler

### What versions are you using?

3.106.0

### What operating system and version are you using?

MacOS

### Please provide a link to a minimal reproduction

_No response_

### Describe the Bug

AKA we should support self defined `WorkerEntrypoint` better.

Consider this worker

```ts
// ./src/server.ts
import { WorkerEntrypoint } from "cloudflare:workers";

export class MyWorker extends WorkerEntrypoint {
someMethod() {
return "hello " + Math.random();
}
}

export default {
async fetch(request: Request, env: Env, ctx: ExecutionContext) {
return Response.json(await env.MyWorker.someMethod());
}
}

```

with this `wrangler.toml`:
```toml
name = "example-worker"
main = "src/server.ts"
compatibility_date = "2025-01-28"

[[services]]
binding = "MyWorker"
service = "example-worker" # this shouldn't be necessary
entrypoint = "MyWorker"
```

2 problems here:

- `service = "example-worker"` shouldn't be ncessary since it's in the same worker. it should default to the main worker. but removing that line causes validation to fail.
- when running `wrangler dev`, I get this output

That seems wrong, since it connects to itself successfully. Thankfully the worker still functions.

### Please provide any relevant error logs

_No response_

Reproduce the configuration in wrangler.toml using the WorkerEntrypoint defined in src/server.ts, first testing validation with service omitted and then running wrangler dev. The work is done when same-worker services accept the omitted field and the dev output no longer reports an incorrect connection state.

Written by the indexing model from the issue text.