Drop kernel variation of reprotest

With kernel variation, build failed with "kernel too old" error.
8 jobs for master in 31 minutes and 14 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #285525
build

00:04:33

 
  Test
passed #285530
autopkgtest

00:03:54

passed #285531
blhc

00:01:32

passed #285529
lintian

00:01:49

passed #285532
piuparts

00:08:54

failed #285528
reprotest

00:03:54

passed #285527
test-build-all

00:04:06

passed #285526
test-build-any

00:04:00

 
Name Stage Failure
failed
reprotest Test
        if ( cleanup ); then :; else echo >&2 "cleanup failed with exit code $?"; fi;
fi
exit $__x
fi" failed with status 2
Uploading artifacts...
/builds/debian/gdbm/debian/output/reprotest: found 12 matching files
/builds/debian/gdbm/debian/output/reprotest.log: found 1 matching files

Uploading artifacts to coordinator... ok
id=285528 responseStatus=201 Created token=HKDeUZZF
ERROR: Job failed: exit code 1