nginx config: Remove worker_processes and events.worker_connections.

This is closer to the default nginx settings with respect to concurrency.

Turn off access log, as it is heavy on I/O and would not be used in a
production setup (whether with or without gVisor).

Update nginx to version `1.25.1`.

PiperOrigin-RevId: 551669286

images/benchmarks/nginx/Dockerfile

@@ -1,4 +1,4 @@
-FROM nginx:1.15.10
+FROM nginx:1.25.1
 
 # Generate a bunch of relevant files.
 RUN mkdir -p /local && \
@@ -8,5 +8,5 @@ RUN mkdir -p /local && \
 
 RUN touch /local/index.html
 
-COPY ./nginx.conf /etc/nginx/nginx.conf
+COPY ./nginx.conf       /etc/nginx/nginx.conf
 COPY ./nginx_gofer.conf /etc/nginx/nginx_gofer.conf

images/benchmarks/nginx/nginx.conf

@@ -1,17 +1,13 @@
-user  nginx;
-worker_processes  1;
+user   nginx;
 daemon off;
 
-error_log  /var/log/nginx/error.log warn;
-pid        /var/run/nginx.pid;
-
-events {
-    worker_connections  1024;
-}
-
+error_log /var/log/nginx/error.log warn;
+pid       /var/run/nginx.pid;
 
+events {}
 http {
     server {
+      access_log off;
       location / {
         root /tmp/html;
       }

images/benchmarks/nginx/nginx_gofer.conf

@@ -1,17 +1,13 @@
-user  nginx;
-worker_processes  1;
+user   nginx;
 daemon off;
 
-error_log  /var/log/nginx/error.log warn;
-pid        /var/run/nginx.pid;
-
-events {
-    worker_connections  1024;
-}
-
+error_log /var/log/nginx/error.log warn;
+pid       /var/run/nginx.pid;
 
+events {}
 http {
     server {
+      access_log off;
       location / {
         root /local;
       }