Fix Insertion point marker shown without the Inserter open

[dratwas]

This PR fixes an inserter point since it is rendered even if shouldn't

Gutenberg PR - WordPress/gutenberg#20195

To test:

• Remove all from initial html
• Click Add Block button
• The inserter should be shown instead of paragraph placeholder - below the title
• Add group block
• Add a block in that group
• The inserter shouldn't be visible after that action and should be in the right place when the bottom sheet is open (please swipe bottom sheet a bit to see if inserter is in the right place)
• Click and hold on the Add Button (long press) and chose add before or add after and check if inserter is in the right place

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[pinarol]

LGTM!