Content dependencies lost on export and importing again if the content entities do not exist

Problem/Motivation

Content dependencies are also soft dependencies. This missing that if they are missing then the configuration should not remove them if resaved. This means that if the content does not exist during configuration import and the config entity is created the content dependency should not be removed. For example, Block content blocks lose their dependencies when exported after being imported before the block content entity existed.

If I have a module that provides some block placements and default content for the block entities themselves, the block placements are imported first and then the block content. This is allowed because of the fallback plugin for blocks. If you immediately attempt to re-export the block placements, the dependencies will be lost.

Steps to reproduce

1. Install Drupal with Standard profile
2. Extract https://www.drupal.org/files/issues/2025-07-15/test_content.tar_.gz → into a custom module folder
3. drush en -y test_content
4. drush config-get block.block.testblock
5. Note, the content dependency has been lost, refer to config/install/block.block.testblock.yml
6. Re-save "Test Block" on the blocks page.
7. drush config-get block.block.testblock - Now shows the dependencies again.

Proposed resolution

Don't clear out content dependencies when recalculating configuration dependencies.

Remaining tasks

Discuss approach, review patch, add tests.

User interface changes

None

API changes

tba

Data model changes

tba