Optimize preload paths for post and site editors

[jsnajdr]

This patch optimizes preload paths in post and site editor so that they match the real requests:

• remove the / preload as the payload is very big and the response is not needed on any critical path
• modify the preloaded path for /wp/v2/taxonomies so that it corresponds to what loadTaxonomyEntities requests. After Gutenberg version that ships the Load the entities list using the view context gutenberg#37685 patch is merged to core, these preloads will need to be further modified to use context=view instead of context=edit.
• modify the /wp/v2/users/me path so that it matches the real request (no query params)
• add a preload of /wp/v2/settings because it's requested on critical path (editor boot). Site editor already preloads this, we're just adding it to the post editor.

This is companion to Gutenberg PR WordPress/gutenberg#39256 which introduces compat code to modify the preload paths with a filter, when a Gutenberg plugin is active.

Fixes https://core.trac.wordpress.org/ticket/55337

[audrasjb]

Committed in https://core.trac.wordpress.org/changeset/52995