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

…12643)

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)

changelog/unreleased/kong/fix-default-value-of-upstream-keepalive-max-requests.yml

@@ -0,0 +1,5 @@
+message: |
+    Fixed default value in kong.conf.default documentation from 1000 to 10000
+    for upstream_keepalive_max_requests option.
+type: bugfix
+scope: Configuration