test: reload knotd after committing all zone changes

test: reload knotd after committing all zone changes

Otherwise, on Ubuntu, the DS RRs sometimes won't get propagated
correctly to parent zones for some reason, ending in a loop:

```
knotd[70]: info: [test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [signed.test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [signed.test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [signed.test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [signed.test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [signed.test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [signed.test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [signed.test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
knotd[70]: info: [signed.test.] DS check, outgoing, remote 10.0.0.1@53, KSK submission check: negative
...
```

causing DNSSEC verification fails. I'm not sure why that happens (yet)...