fix: compress-response only on http response (#1317)

Changing to be `on_http_response` only until we fix this.

Author: nijikokun

traffic-policy/actions/compress-response/config.mdx

@@ -12,7 +12,7 @@ reference for this action.
 
 #### Supported Phases
 
-`on_http_request`, `on_http_response`
+`on_http_response`
 
 #### Type