[AI Bundle][Ollama] Fix configuration when a custom http_client is set

[lyrixx]

Q	A
Bug fix?	yes
New feature?	no
Docs?	no
Issues	Fix #766
License	MIT

cc @Guikingone

[lyrixx]

If we don't do that, we use the default HTTP Client.
And I have the following options:

ai:
    platform:
        ollama:
            http_client: http_client.ollama
            # Configured in the HTTP Client
            # see https://github.com/symfony/ai/issues/899
            host_url: ''
            api_catalog: true

So host_url is empty, so the underlying code will explode because the host URL is not a valid endpoint

[Guikingone]

If I'm right host_url can be omitted (as it fallback to http://127.0.0.1:11434 by default) 🤔

                    ->arrayNode('ollama')
                        ->children()
                            ->stringNode('host_url')->defaultValue('http://127.0.0.1:11434')->end()
                            ->stringNode('http_client')
                                ->defaultValue('http_client')
                                ->info('Service ID of the HTTP client to use')
                            ->end()
                            ->booleanNode('api_catalog')
                                ->info('If set, the Ollama API will be used to build the catalog and retrieve models information, using this option leads to additional HTTP calls')
                            ->end()
                        ->end()
                    ->end()

[lyrixx]

But if someone configure a custom host_url, without a custom HTTP client, the one in the configure must be used. So it cannot be omitted

[chr-hertel]

Thank you @lyrixx.