fix logic bug in wasValidatorDownForIntervals (#5917)

if you want to use .some, then return value should have been negated. but using .every is way more intuitive.

### Description

Fixes simple logic bug.

### Other changes

### Tested

### Related issues

### Backwards compatibility

packages/contractkit/src/wrappers/DowntimeSlasher.ts

@@ -158,7 +158,7 @@ export class DowntimeSlasherWrapper extends BaseSlasher<DowntimeSlasher> {
     const downArray = await Promise.all(
       intervals.map((interval) => this.wasValidatorDownForInterval(address, interval))
     )
-    return downArray.some((down) => !down)
+    return downArray.every((down) => down)
   }
 
   /**