Dynamically update "dynamic" field setting default value in Mappings Editor

[cjcenizal]

Problem

Per conversation with @crisdarocha, if you set the index-level dynamic setting to false, this change isn't surfaced in the field-level dynamic setting:

What's confusing about this is that simply opening and closing the editor flyout for the field will affect the underlying ES request in confusing ways. If the user doesn't open the editor, the request doesn't specify a field-level dynamic setting, resulting in ES applying the index-level dynamic: false setting to this field:

However, if the user opens and closes the editor (without changing any settings), the request will specify a field-level dynamic: true setting, which results in ES different behavior than above:

Somewhat related to #52708, because this issue involves the application of ES defaults to the ES request.

Proposed solution

We can address this by dynamically (pun!) changing the dynamic field-level setting's default value, to match whatever has been set on index-level. This way when users edit a field they will see a default value for this setting that matches their expectations if they've changed the index-level setting. Per @sebelga this implementation should be straightforward. More time will be spent writing the tests than the implementation.

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[sebelga]

I think we still need to address #52708 to solve this issue (stripping out any setting that has not been modified by the user. This should be done at the form lib level with an option on the form).

The reason is: there is the possibility for a user to

1. Create an object, open the flyout, click save
2. He now has dynamic: true on the object
3. He changes the index level dynamic settings
4. His initial object is still with dynamic: true

If we had stripped away the dynamic: true when clicking "Update" on the button, it would be undefined.

At this point the user can safely:

• Turn off the index level dynamic setting
• edit the object he created --> the dynamic toggle would now be off (once we have synced the defaultValue for the field to that value)