fix(influxdb3): add show_deleted parameter for listing databases (#6631)

Add the show_deleted query parameter to the list databases endpoint
in the Enterprise API spec. This parameter allows users to include
soft-deleted databases in the response.

closes #6610

api-docs/influxdb3/enterprise/v3/ref.yml

@@ -1042,6 +1042,15 @@ paths:
       description: Retrieves a list of databases.
       parameters:
         - $ref: '#/components/parameters/formatRequired'
+        - name: show_deleted
+          in: query
+          required: false
+          schema:
+            type: boolean
+            default: false
+          description: |
+            Include soft-deleted databases in the response.
+            By default, only active databases are returned.
       responses:
         '200':
           description: Success. The response body contains the list of databases.