Add warnings about scaling issues with ajax and webcron

[nickvergessen]

Green sections have been added:

[szaimen]

@nickvergessen would it make sense to also add a warning to the admin overview if more than e.g. 5 users are present and webcron is used?
Same for ajax and one user?

[nickvergessen]

The red warning that jobs are not executed should be enough? e.g. screenshot from nextcloud/server#31725

[szaimen]

The red warning that jobs are not executed should be enough? e.g. screenshot from nextcloud/server#31725

does this also show up in the admin overview?

I would also make the wording more explicit. E.g. add what is recommended to do in those cases...

[nickvergessen]

does this also show up in the admin overview?

I guess not. Feel free to add it then.

[szaimen]

does this also show up in the admin overview?

I guess not. Feel free to add it then.

will do, thanks :)

[szaimen]

There is actually already a warning in the overview that links to the cron settings page. So lets make the description of each setting a bit more verbose...

[nickvergessen]

/backport to stable24

[nickvergessen]

/backport to stable23

[nickvergessen]

/backport to stable22