Investigate and migrate default configuration

[Xzelsius]

According to validation actions, default.json config should be migrated.

DEBUG: Checking for config file in /home/runner/work/renovate-config/renovate-config/default.json
 WARN: Config needs migrating
       "originalConfig": {
         "$schema": "https://docs.renovatebot.com/renovate-schema.json",
         "description": "Default configuration for all my repositories.",
         "extends": [
           "config:base",
           ":semanticCommits",
           ":semanticCommitTypeAll(chore)",
           ":semanticCommitScope(deps)"
         ],
         "rebaseWhen": "behind-base-branch",
         "assignees": ["Xzelsius"],
         "labels": ["dependencies"]
       },
       "migratedConfig": {
         "$schema": "https://docs.renovatebot.com/renovate-schema.json",
         "description": "Default configuration for all my repositories.",
         "extends": [
           "config:recommended",
           ":semanticCommits",
           ":semanticCommitTypeAll(chore)",
           ":semanticCommitScope(deps)"
         ],
         "rebaseWhen": "behind-base-branch",
         "assignees": ["Xzelsius"],
         "labels": ["dependencies"]
       }
 INFO: Validating default.json

Investigate differences between config:base and config:recommended and why they recommend migrating.
If this does not introduce a bunch of unwanted rules, it should be migrated.