Config schema errors when choosing layouts that have multiple regions

Problem/Motivation

This warning is thrown on D11 because region is expecting a "content" key only but this only exists for layout_onecol:

Schema errors for core.entity_view_display.node.article.default with the following errors: core.entity_view_display.node.article.default:third_party_settings.layout_builder.sections.1.layout_settings.regions.top missing schema, core.entity_view_display.node.article.default:third_party_settings.layout_builder.sections.1.layout_settings.regions.first missing schema, core.entity_view_display.node.article.default:third_party_settings.layout_builder.sections.1.layout_settings.regions.second missing schema, core.entity_view_display.node.article.default:third_party_settings.layout_builder.sections.1.layout_settings.regions.third missing schema, core.entity_view_display.node.article.default:third_party_settings.layout_builder.sections.1.layout_settings.regions.fourth missing schema, core.entity_view_display.node.article.default:third_party_settings.layout_builder.sections.1.layout_settings.regions.bottom missing schema. These errors mean there is configuration that does not comply with its schema. This is not a fatal error, but it is recommended to fix these issues. For more information on configuration schemas, check out the documentation.

Steps to reproduce

1. Enable layout builder for any content type.
2. Add a new section and select a layout other than layout_onecol.
3. Add blocks to the regions and save configuration.

Proposed resolution

Replace config declaration from using config_entity to just a regular sequence and mapping so they are dynamic.