perform a more complete cleanup after running system tests [rt41255]

(cherry picked from commit ecfedec0e0)

Conflicts:
	bin/tests/system/acl/clean.sh
	bin/tests/system/addzone/clean.sh
	bin/tests/system/allow_query/clean.sh
	bin/tests/system/autosign/clean.sh
	bin/tests/system/case/clean.sh
	bin/tests/system/checknames/clean.sh
	bin/tests/system/dlzexternal/clean.sh
	bin/tests/system/dscp/clean.sh
	bin/tests/system/ednscompliance/clean.sh
	bin/tests/system/emptyzones/clean.sh
	bin/tests/system/formerr/clean.sh
	bin/tests/system/forward/clean.sh
	bin/tests/system/glue/clean.sh
	bin/tests/system/limits/clean.sh
	bin/tests/system/lwresd/clean.sh
	bin/tests/system/masterfile/clean.sh
	bin/tests/system/names/clean.sh
	bin/tests/system/nslookup/clean.sh
	bin/tests/system/nsupdate/clean.sh
	bin/tests/system/sfcache/clean.sh
	bin/tests/system/sit/clean.sh
	bin/tests/system/sortlist/clean.sh
	bin/tests/system/stub/clean.sh
	bin/tests/system/xferquota/clean.sh

(cherry picked from commit f9c9fce5c7)

Conflicts:
	bin/tests/system/digdelv/tests.sh
	bin/tests/system/dlzexternal/clean.sh
	bin/tests/system/formerr/clean.sh
	bin/tests/system/resolver/clean.sh
	bin/tests/system/rndc/clean.sh
	bin/tests/system/rrl/prereq.sh
	bin/tests/system/sit/clean.sh
	bin/tests/system/tkey/clean.sh
	bin/tests/system/zonechecks/clean.sh
	lib/export/isc/nothreads/include/Makefile.in

bin/tests/system/dnssec/clean.sh

@@ -34,6 +34,7 @@ rm -f ns*/*.nta
 rm -f ns*/named.lock
 rm -f ns1/managed.key.id
 rm -f ns1/resolve.key
+rm -f ns1/sample.key
 rm -f ns1/root.db ns2/example.db ns3/secure.example.db
 rm -f ns2/algroll.db
 rm -f ns2/badparam.db ns2/badparam.db.bad