base: Fix error to save configuration at obs_module_unload

[norihiro]

Description

This PR removes _config->Save() from obs_module_unload.

Motivation and Context

Less number of error logs is better.

When obs_module_unload is called, the frontend API is no longer available so that _config->Save() is failing with error messages. Since the configuration is saved from the OK or the Apply button on the dialog, it is not necessary to save it again at obs_module_unload.

How Has This Been Tested?

Tested OS(s): Fedora 37

Run obs and exit it. Checked the log message shows no line below.

Tried to call obs_frontend_get_global_config with no callbacks!
[obs-websocket] [Config::Save] Unable to fetch OBS config!

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• [x] I have read the Contributing Guidelines.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] My code is not on master or a release/* branch.
• [x] The code has been tested.
• [x] I have included updates to all appropriate documentation.