Harden grep key ID calls

Key IDs may accidentally match dig output that is not the key ID (for
example the RRSIG inception or expiration time, the query ID, ...).
Search for key ID + signer name should prevent that, as that is what
only should occur in the RRSIG record, and signer name always follows
the key ID.

(cherry picked from commit 83473b97)
39 jobs for !1851 with matthijs-fix-dnssec-test-intermittent-failure-kskonly-v9_14 in 10 minutes and 45 seconds (queued for 3 seconds)
detached
Status Job ID Name Coverage
  Precheck
passed #219370
linux amd64
🐞:sid:amd64

00:00:37

passed #219369
linux amd64
misc:sid:amd64

00:00:16

 
  Build
passed #219381
linux amd64
asan:sid:amd64

00:01:40

passed #219382
linux amd64
clang:stretch:amd64

00:01:06

passed #219383
linux i386
clang:stretch:i386

00:01:38

passed #219371
linux amd64
docs:sid:amd64

00:00:36

passed #219380
linux amd64
gcc:bionic:amd64

00:02:28

passed #219372
linux amd64
gcc:centos6:amd64

00:01:55

passed #219373
linux amd64
gcc:centos7:amd64

00:01:46

passed #219378
linux amd64
gcc:fedora29:amd64

00:02:15

passed #219374
linux amd64
gcc:jessie:amd64

00:00:58

passed #219376
linux amd64
gcc:sid:amd64

00:01:46

passed #219377
linux i386
gcc:sid:i386

00:01:24

passed #219375
linux amd64
gcc:stretch:amd64

00:01:43

passed #219379
linux amd64
gcc:xenial:amd64

00:01:23

passed #219384
linux amd64
pkcs11:sid:amd64

00:01:22

 
  Test
passed #219403
linux amd64
system:asan:sid:amd64

00:07:38

passed #219401
linux amd64
system:gcc:bionic:amd64

00:06:47

passed #219385
linux amd64
system:gcc:centos6:amd64

00:06:27

passed #219387
linux amd64
system:gcc:centos7:amd64

00:06:17

passed #219397
linux amd64
system:gcc:fedora29:amd64

00:06:59

passed #219389
linux amd64
system:gcc:jessie:amd64

00:06:19

passed #219393
linux amd64
system:gcc:sid:amd64

00:06:56

passed #219395
linux i386
system:gcc:sid:i386

00:06:48

passed #219391
linux amd64
system:gcc:stretch:amd64

00:06:24

passed #219399
linux amd64
system:gcc:xenial:amd64

00:06:20

passed #219406
linux amd64
system:pkcs11:sid:amd64

00:06:36

passed #219404
linux amd64
unit:asan:sid:amd64

00:00:58

passed #219405
linux amd64
unit:clang:stretch:amd64

00:00:48

passed #219402
linux amd64
unit:gcc:bionic:amd64

00:00:43

passed #219386
linux amd64
unit:gcc:centos6:amd64

00:00:48

passed #219388
linux amd64
unit:gcc:centos7:amd64

00:00:45

passed #219398
linux amd64
unit:gcc:fedora29:amd64

00:00:50

passed #219390
linux amd64
unit:gcc:jessie:amd64

00:00:31

passed #219394
linux amd64
unit:gcc:sid:amd64

00:00:49

passed #219396
linux i386
unit:gcc:sid:i386

00:00:46

passed #219392
linux amd64
unit:gcc:stretch:amd64

00:00:43

passed #219400
linux amd64
unit:gcc:xenial:amd64

00:00:56

passed #219407
linux amd64
unit:pkcs11:sid:amd64

00:00:49