[logcli] set default instead of error for parallel-max-workers valida…

…tion (grafana#8641)

**What this PR does / why we need it**:
Fixes regression reported here:
grafana#8518 (comment)

@dannykopping can you please verify that it fixes the issue for you?

**Checklist**
- [x] Reviewed the
[`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md)
guide (**required**)
- [ ] Documentation added
- [ ] Tests updated
- [ ] `CHANGELOG.md` updated
- [ ] Changes that require user attention or interaction to upgrade are
documented in `docs/sources/upgrading/_index.md`

cmd/logcli/main.go

@@ -428,12 +428,13 @@ func newQuery(instant bool, cmd *kingpin.CmdClause) *query.Query {
 
 			q.Start = mustParse(from, defaultStart)
 			q.End = mustParse(to, defaultEnd)
-		}
-		q.Quiet = *quiet
 
-		if q.ParallelMaxWorkers < 1 {
-			return fmt.Errorf("parallel-max-workers must be greater than 0")
+			if q.ParallelMaxWorkers < 1 {
+				log.Println("parallel-max-workers must be greater than 0, defaulting to 1.")
+				q.ParallelMaxWorkers = 1
+			}
 		}
+		q.Quiet = *quiet
 
 		return nil
 	})