Old navigation block (without alignment) still offered in quick-inserter

[strarsis]

Describe the bug
When the "quick" inserter is opened (Ctrl + 7) hotkey, the old core/navigation block,
without alignment (horizontal/vertical) is still offered to the user and can be selected and inserted.

To reproduce
Steps to reproduce the behavior:

1. Open the "quick" inserter (Ctrl + 7 hotkey or other means) and select the navigation block labeled Navigation. Notice that the block is inserted. If you hadn't inserted a navigation block recently, the "quick" inserter may not offer it.
   Also notice that old posts/pages, that had been edited before the introduction of the new core/navigation block types can still contain old navigation blocks.

Expected behavior
The old core/navigation block shouldn't be in the ("quick") inserter list anymore,
when the new navigation blocks (horizontal/vertical) are now offered in Gutenberg.
This could be a bug more related to the "quick" inserter feature and not specifically to the navigation blocks though.
It may also be a good idea to offer a transform to the old core/navigation blocks,
or use the old navigation block as horizontal default, but this would require to remove the Navigation (horizontal) block and relabel the old navigation block to Navigation (horizontal)

Editor version (please complete the following information):

• WordPress version: v5.4.1
• Does the website has a Gutenberg plugin installed, or is it using the block editor that comes by default? Gutenberg Plugin
• If the Gutenberg plugin is installed, which version is it? v8.0.0

Desktop (please complete the following information):

• OS: Windows 10 x64 Pro
• Browser: Chrome
• Version: 81.0.4044.129

Additional context

[talldan]

Hey @strarsis, the two navigation blocks are implemented using Block Variations. The inserter issue is known and tracked on #20583, so I'll close this as a duplicate.