Refactor termination and rental object entities

- Removed the "Kündigungen" field from the German and English rental object JSON files.
- Updated the termination JSON files to reflect new field names and structure, including renaming "kuendigungsart" to "beendigungsTatbestand" and "kuendigungsgrund" to "kuendigungsgrund" with updated options.
- Deleted the old "CKuendigung" entity definition and related metadata, consolidating functionality into "CKndigung".
- Adjusted the service logic to accommodate the new structure, ensuring proper linking of landlords and tenants.
- Updated dynamic visibility logic for fields based on conditions related to termination reasons and delivery methods.
- Cleaned up metadata definitions for both termination and rental object entities, removing unnecessary relationships and fields.
- Incremented cache and microtime values in the configuration file.

custom/Espo/Custom/Resources/metadata/entityDefs/CMietobjekt.json

@@ -157,14 +157,6 @@
             "entity": "CMietinkasso",
             "audited": false,
             "isCustom": true
-        },
-        "kndigungen": {
-            "type": "hasMany",
-            "relationName": "cMietobjektKuendigung",
-            "foreign": "mietobjekte",
-            "entity": "CKndigung",
-            "audited": false,
-            "isCustom": true
         }
     },
     "collection": {