test: drop forgotten set +e

This was introduced all the way back in 2019 where this particular test
case was the last one in the file, so it worked as intended.
Unfortunately, since then we added new tests after this one, which means
this particular `set +e` masked fails in any of them (except for
assert_*() calls, which call exit on fail).

test/units/TEST-03-JOBS.sh

@@ -98,14 +98,11 @@ ELAPSED=$((END_SEC-START_SEC))
 
 # Test time-limited scopes
 START_SEC=$(date -u '+%s')
-set +e
-systemd-run --scope --property=RuntimeMaxSec=3s sleep 30
-RESULT=$?
+(! systemd-run --scope --property=RuntimeMaxSec=3s sleep 30)
 END_SEC=$(date -u '+%s')
 ELAPSED=$((END_SEC-START_SEC))
 [[ "$ELAPSED" -ge 3 ]]
 [[ "$ELAPSED" -le 10 ]]
-[[ "$RESULT" -ne 0 ]]
 
 # Test transactions with cycles
 # Provides coverage for issues like https://github.com/systemd/systemd/issues/26872
@@ -121,7 +118,9 @@ EOF
 done
 systemctl daemon-reload
 for i in {0..19}; do
-    systemctl start "transaction-cycle$i.service"
+    # This intentionally fails with:
+    #   Failed to start transaction-cycle0.service: Transaction order is cyclic. See system logs for details.
+    systemctl start "transaction-cycle$i.service" || :
 done
 
 IDS_FILE="/tmp/TEST-03-JOBS-CYCLE-IDS-$RANDOM"
@@ -168,6 +167,8 @@ assert_rc 3 systemctl --quiet is-active succeeds-on-restart.target
 systemctl start fails-on-restart.target || :
 assert_rc 3 systemctl --quiet is-active fails-on-restart.target
 
+systemctl stop fails-on-restart.service
+
 COUNTER_FILE=/tmp/test-03-restart-counter
 export FAILURE_FLAG_FILE=/tmp/test-03-restart-failure-flag