docs: rename assigned_team_first_response_time to assigned_team_first_response_time_by_team

Update the field name across all affected API versions (0, 2.12, 2.13, 2.14, 2.15) to align with the actual API response. The field `assigned_team_first_response_time_in_office_hours` is unchanged.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: VarshSuresh

descriptions/0/api.intercom.io.yaml

@@ -21674,7 +21674,7 @@ components:
           type: integer
           description: Total number of conversation parts.
           example: 1
-        assigned_team_first_response_time_by_team:
+        assigned_team_first_response_time:
           type: array
           description: An array of conversation response time objects
           items:

descriptions/2.12/api.intercom.io.yaml

@@ -14534,7 +14534,7 @@ components:
           type: integer
           description: Total number of conversation parts.
           example: 1
-        assigned_team_first_response_time_by_team:
+        assigned_team_first_response_time:
           type: array
           description: An array of conversation response time objects
           items:

descriptions/2.13/api.intercom.io.yaml

@@ -15953,7 +15953,7 @@ components:
           type: integer
           description: Total number of conversation parts.
           example: 1
-        assigned_team_first_response_time_by_team:
+        assigned_team_first_response_time:
           type: array
           description: An array of conversation response time objects
           items:

descriptions/2.14/api.intercom.io.yaml

@@ -17375,7 +17375,7 @@ components:
           type: integer
           description: Total number of conversation parts.
           example: 1
-        assigned_team_first_response_time_by_team:
+        assigned_team_first_response_time:
           type: array
           description: An array of conversation response time objects
           items:

descriptions/2.15/api.intercom.io.yaml

@@ -18102,7 +18102,7 @@ components:
           type: integer
           description: Total number of conversation parts.
           example: 1
-        assigned_team_first_response_time_by_team:
+        assigned_team_first_response_time:
           type: array
           description: An array of conversation response time objects
           items: