ignore EINVAL when flushing logs (#238)

* ignore EINVAL when flushing logs

Running the `scheduler` in EKS, every 5 mins an error is logging:

```
failed to flush logs: sync /dev/stderr: invalid argument
```

uber-go/zap#328 details the pain here which comes down to stderr not being syncable in all environments.

* Update cmd/scheduler/app/server.go

Co-authored-by: Omri Cohen <[email protected]>

---------

Co-authored-by: Omri Cohen <[email protected]>

Author: slaupster

cmd/scheduler/app/server.go

@@ -47,7 +47,8 @@ var logFlushFreq = pflag.Duration("log-flush-frequency", 5*time.Second, "Maximum
 
 func flushLogs() {
 	if err := log.InfraLogger.Sync(); err != nil &&
-		!errors.Is(err, syscall.ENOTTY) { // https://github.com/uber-go/zap/issues/991#issuecomment-962098428
+		!errors.Is(err, syscall.ENOTTY) && // https://github.com/uber-go/zap/issues/991#issuecomment-962098428
+		!errors.Is(err, syscall.EINVAL) { // https://github.com/uber-go/zap/issues/328
 		fmt.Fprintf(os.Stderr, "failed to flush logs: %v\n", err)
 	}
 }