Remove features from Social Group module

Problem

See problem definition in #3092272: [Meta] Moving away from features.

Solution

• Remove the module.features.yml file
• Move the default editable config from hook_install() into a module's config/install/*.yml file.
• If hook_install alters configuration from other modules, consider whether we should include the config file in the profile's config/install folder to overwrite it instead
• Remove any _module_set_defaults function

Steps to reproduce

• Enable all changed modules
• See that none of them install configuration provided by other modules
• Change configuration for each module
• Revert features

Expected result (after fix)

The changed configuration keeps its changes.

Actual result

The changed configuration is reverted to default values.