Correct the integration test

t/apicast-policy-request-unbuffered.t

@@ -61,9 +61,10 @@ server_name test-upstream.lvh.me;
 --- response_body eval chomp
 $ENV{LARGE_BODY}
 --- error_code: 200
---- grep_error_log
-a client request body is buffered to a temporary file
+--- grep_error_log eval
+qr/a client request body is buffered to a temporary file/
 --- grep_error_log_out
+a client request body is buffered to a temporary file
 --- no_error_log
 [error]
 
@@ -107,7 +108,6 @@ server_name test-upstream.lvh.me;
   location / {
     access_by_lua_block {
       assert = require('luassert')
-      ngx.say("yay, api backend")
 
       -- Nginx will read the entire body in one chunk, the upstream request will not be chunked
       -- and Content-Length header will be added.
@@ -203,8 +203,9 @@ $s
 --- response_body eval
 $::data
 --- error_code: 200
---- grep_error_log
-a client request body is buffered to a temporary file
+--- grep_error_log eval
+qr/a client request body is buffered to a temporary file/
 --- grep_error_log_out
+a client request body is buffered to a temporary file
 --- no_error_log
 [error]