ta_sentinel: fix is/not logic

I got confused by the original text in
draft-ietf-dnsop-kskroll-sentinel-00 and inverted meaning of is/not
sentinel queries.
16 jobs for draft-ietf-dnsop-kskroll-sentinel-01 in 9 minutes and 49 seconds (queued for 7 seconds)
Status Job ID Name Coverage
  Build
passed #109867
docker linux amd64
build:clang:linux:amd64

00:00:28

passed #109866
docker linux amd64
build:linux:amd64

00:00:27

 
  Test
passed #109874
docker linux amd64
deckard:linux:amd64

00:06:38

passed #109873
docker
doc

00:00:39

passed #109872
docker linux amd64
installcheck:linux:amd64

00:00:51

passed #109875
docker linux amd64
installcheck:valgrind:linux:amd64

00:01:24

passed #109869
docker
lint:c

00:02:06

failed #109870
docker allowed to fail
lint:clang-scan-build

00:00:59

passed #109868
docker
lint:lua

00:00:29

passed #109930
docker linux amd64
respdiff:iter:tcp:linux:amd64

00:02:25

passed #109879
docker linux amd64
respdiff:iter:tls:linux:amd64

00:02:28

passed #109877
docker linux amd64
respdiff:iter:udp:linux:amd64

00:02:28

passed #109871
docker linux amd64
test:linux:amd64

00:00:46

passed #109876
docker linux amd64
test:linux:amd64:valgrind

00:00:42

failed #109878
docker linux amd64
respdiff:iter:tcp:linux:amd64

00:05:58

 
  Coverage
passed #109880
docker linux amd64
coverage

00:00:14

71.5%
 
Name Stage Failure
failed
lint:clang-scan-build Test
                                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5 warnings generated.
CCLD daemon/kresd
scan-build: 22 bugs found.
scan-build: Run 'scan-view /builds/knot/knot-resolver/scan-results/2018-02-15-144932-14-1' to examine bug reports.
Uploading artifacts...
scan-results: found 27 matching files
Uploading artifacts to coordinator... ok
id=109870 responseStatus=201 Created token=NBgxvhxe
ERROR: Job failed: exit code 1