fix: replace Instance Settings with Default Settings in i18n and docs (#8143)

# Which Problems Are Solved

- The console shows the Instance Settings title and a description.
Instance settings should be replaced with Default settings

# How the Problems Are Solved

- The DESCRIPTIONS.SETTINGS.INSTANCE.TITLE and
DESCRIPTIONS.SETTINGS.INSTANCE.DESCRIPTION have been replaced with
Default Settings and in the corresponding translation files.

Here's a screenshot:


![image](https://github.com/zitadel/zitadel/assets/30386061/b404f209-2043-414c-b06d-3291771d54fb)

# Additional Changes

- The docs have been updated to replace remaining texts mentioning
Instance Settings with Default Settings
- Two unused texts have been deleted from the translation files
- VSCode with Prettier have applied some markdown changes

# Additional Context

- Closes #7632

---------

Co-authored-by: Fabi <fabienne@zitadel.com>

console/src/assets/i18n/sv.json

@@ -79,8 +79,8 @@
     },
     "SETTINGS": {
       "INSTANCE": {
-        "TITLE": "Instansinställningar",
-        "DESCRIPTION": "Instansinställningarna är standardinställningarna för alla organisationer. Med rätt behörigheter kan vissa av dem åsidosättas i organisationsinställningarna."
+        "TITLE": "Standardinställningar",
+        "DESCRIPTION": "Standardinställningar för alla organisationer. Med rätt behörigheter kan vissa av dem åsidosättas i organisationsinställningar."
       },
       "ORG": {
         "TITLE": "Organisationsinställningar",