Fix conf.has_option not respects default provider metadata

[jason810496]

• closes: SDK conf does not resolve provider metadata config defaults (has_option returns False) #64201

Noted that all the ProviderManger includes RuntimeProviderManager, I just shorten as ProviderManger to refer both of them.

What

TL;DR;

Cleanup for deprecated path for the new "make conf respect provider metadata" mechanism.

The write(include_providers=True), with conf.make_sure_configuration_loaded(with_providers=False) or any conf.as_dict are the caller that introduce the recursive call between conf module and Provider Manager, so it would be better to clean them up in case they cause more regression just because we need to maintain those interfaces.

Before the clean up: configuration_description as stateful attributes

• we need load_providers_configuration, restore_core_default_configuration to change the state of configuration_description just to reflect the sources of the conf
• the configuration_description before the cleanup will not respect _provider_cfg_config_fallback_default_values or _provider_metadata_config_fallback_default_values.

After the current clean up: configuration_description as view

• configuration_description is now a cache_property that can reflect _provider_cfg_config_fallback_default_values and _provider_metadata_config_fallback_default_values config sources

Was generative AI tooling used to co-author this PR?

• Yes, Claude Code for fixing the unit tests