Update gitea.service (#21399)

`LimitMEMLOCK=infinity` is already the default, so removed that

Default soft limit for LimitNOFILE is 1024
Default hard limit for LimitNOFILE is 524288

`LimitNOFILE=65535` increases the soft limit, but decreases the hard
limit

References:
* https://www.freedesktop.org/software/systemd/man/systemd.exec.html
*
https://blog.skbali.com/2019/09/set-ulimits-for-a-script-started-using-systemd/

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

Author: 3 people

contrib/systemd/gitea.service

@@ -49,12 +49,8 @@ After=network.target
 ###
 
 [Service]
-# Modify these two values and uncomment them if you have
-# repos with lots of files and get an HTTP error 500 because
-# of that
-###
-#LimitMEMLOCK=infinity
-#LimitNOFILE=65535
+# Uncomment the next line if you have repos with lots of files and get a HTTP 500 error because of that
+# LimitNOFILE=524288:524288
 RestartSec=2s
 Type=simple
 User=git