fix(conf): fix the default value of upstream_keepalive_max_requests (#…

…12647)

This commit fixes the discrepancy between the default value of
upstream_keepalive_max_requests in the Kong.conf comments and the actual value
in kong/templates/kong_defaults.lua.

(cherry picked from commit c5ed954)

---------

Co-authored-by: Xiaochen Wang <wangxiaochen0@gmail.com>

kong.conf.default

@@ -1016,7 +1016,7 @@
                                      # each upstream request to open a new
                                      # connection.
 
-#upstream_keepalive_max_requests = 1000  # Sets the default maximum number of
+#upstream_keepalive_max_requests = 10000 # Sets the default maximum number of
                                          # requests than can be proxied upstream
                                          # through one keepalive connection.
                                          # After the maximum number of requests