When the scheduler assigns a device instance, it iterates over the feasible
devices and then picks the first instance with availability. If the jobspec uses
a constraint on device ID, this can lead to buggy/surprising behavior where the
node's device matches the constraint but then the individual device instance
does not.
Add a second filter based on the `${device.ids}` constraint after selecting a
node's device to ensure the device instance ID falls within the constraint as
well.
Fixes: #18112
This adds constraints for asserting that a given attribute or value
exists, or does not exist. This acts as a companion to =, or !=
operators, e.g:
```hcl
constraint {
attribute = "${attrs.type}"
operator = "!="
value = "database"
}
constraint {
attribute = "${attrs.type}"
operator = "is_set"
}
```
Also changes the logic for score when there is more than one task
requesting a device. Since inter task affinities are already normalized,
we take the average of the scores across tasks.
Tim Gross