[Feature Request] Remove automatic `_disableToc` set condition

**Is your feature request related to a problem? Please describe.**
On current docfx implementation.
docfx automatically disable TOC Area when (`model._navPath === model._tocPath`) condition met.

This behavior is not documented and it's confusing for user.
who using top-level `toc.yml` for both top-navigation and TOC.

This behavior can be changed by explicitly set `disableToc:false` or `_layout: landing` setting.
So I willing to remove this condition from template.

**Describe the solution you'd like**
Remove (`model._navPath === model._tocPath`) condition from following files.

- [conceptual.html.primary.js](https://github.com/filzrev/docfx/blob/fe56b5addb1447977a2890e8bd812f6be087cf0d/templates/default/conceptual.html.primary.js#L13)
- [ManagedReference.html.primary.js](https://github.com/filzrev/docfx/blob/main/templates/default/ManagedReference.html.primary.js#L27)
- [RestApi.html.primary.js](https://github.com/filzrev/docfx/blob/main/templates/default/RestApi.html.primary.js#L16)
- [UniversalReference.html.primary.js](https://github.com/filzrev/docfx/blob/main/templates/default/UniversalReference.html.primary.js#L17)

**Additional context**
This change introduce **BREAKING CHANGES** for existing users.