Raise Heat API WSGI timeout to 600s

The HAProxy and Heat's rpc_response_timeout are already set to 10
minutes, so the WSGI timeout should be as well. Otherwise, raising the
other timeouts doesn't really do any good.

Some requests to the Heat API when running config-download can take
longer than 60 seconds, particularly at scale (> 100 nodes).

Change-Id: I466afb53bee498c6f265ecf613fe34a736c6b92e
Closes-Bug: #1860475

deployment/heat/heat-base-puppet.yaml

@@ -186,3 +186,4 @@ outputs:
             heat::cron::purge_deleted::age_type: {get_param: HeatCronPurgeDeletedAgeType}
             heat::cron::purge_deleted::destination: {get_param: HeatCronPurgeDeletedDestination}
             heat::max_json_body_size: {get_param: HeatMaxJsonBodySize}
+            heat::wsgi::apache::vhost_custom_fragment: 'Timeout 600'

releasenotes/notes/heat-api-wsgi-timeout-600-640058f1ae18232c.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - The WSGI timeout for Heat API is now set to 600 seconds to match the
+    HAProxy timeout and the RPC response timeout. Previously, it was set to 60
+    seconds, which resulted in API requests timing out.