When the workers option for rspamd was originally implemented it was
based on a flawed understanding of how workers are configured in rspamd.
This meant that while rspamd supports configuring multiple workers of
the same type, so that different controller workers could have different
passwords, the NixOS module did not support this because it would write
an invalid configuration file if you tried.
Specifically a configuration like the one below:
```
workers.controller = {};
workers.controller2 = {
type = "controller";
};
```
Would result in a rspamd configuration of:
```
worker {
type = "controller";
count = 1;
.include "$CONFDIR/worker-controller.inc"
}
worker "controller2" {
type = "controller";
count = 1;
}
```
While to get multiple controller workers it should instead be:
```
worker "controller" {
type = "controller";
count = 1;
.include "$CONFDIR/worker-controller.inc"
}
worker "controller" {
type = "controller";
count = 1;
}
```