Revert "Update base nginx" (#7558)

* Revert "Update base nginx (#7552)"

This reverts commit c6bc9870f1.

* keep alpine bump

images/nginx/rootfs/patches/nginx-1.19.9-upstream_pipelining.patch

@@ -1,23 +0,0 @@
-commit f9907b72a76a21ac5413187b83177a919475c75f
-Author: Yichun Zhang (agentzh) <agentzh@gmail.com>
-Date:   Wed Feb 10 16:05:08 2016 -0800
-
-    bugfix: upstream: keep sending request data after the first write attempt.
-    
-    See
-    http://mailman.nginx.org/pipermail/nginx-devel/2012-March/002040.html
-    for more details on the issue.
-
-diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
-index 69019417..92b7c97f 100644
---- a/src/http/ngx_http_upstream.c
-+++ b/src/http/ngx_http_upstream.c
-@@ -2239,7 +2239,7 @@ ngx_http_upstream_send_request_handler(ngx_http_request_t *r,
-
- #endif
-
--    if (u->header_sent && !u->conf->preserve_output) {
-+    if (u->request_body_sent && !u->conf->preserve_output) {
-         u->write_event_handler = ngx_http_upstream_dummy_handler;
-
-         (void) ngx_handle_write_event(c->write, 0);