Drop the never-ran reading: a start timestamp of 0 does not mean a one-shot never ran (issue 1126)

Review round 1 measured it on systemd 262.1: a finished one-shot nothing references is
unloaded, and loaded again it reads inactive, ExecMainStatus=0 and a start timestamp of
0, as one that never ran does. The previous commit's rule read such a unit stopped, so
a one-shot declared running would be started, read stopped and fail on every apply, and
the hold, the take-over and the giving back would judge it wrongly.

ServiceState keeps main's reading. ServiceAtRest and declaredState stay: they alone
satisfy a stopped declaration for a one-shot at rest, which is the kernel cleanup's
case. A one-shot declared running that must be seen to have run lingers
(RemainAfterExit) or is enabled at boot. Unit tests: the arch table has 5 rows, the
apply test 1; 1262 in all.

internal/system/arch_test.go

@@ -14,28 +14,19 @@ import (
 // **One that failed is still stopped**, or the host would report success for work that did not
 // happen — the opposite mistake and the worse one.
 //
-// **One that never ran is stopped** (novox/hq issue 1126, the kernel's boot-time cleanup on ace):
-// systemd says ExecMainStatus=0 for a unit that never ran exactly as for one that succeeded, and
-// only its start timestamp separates them. Read as "running", a package's one-shot declared
-// running was never started, and one declared stopped could never be.
-//
-// **At rest** is whether a one-shot that does not linger has nothing running now: a declaration
+// **At rest** (novox/hq issue 1126, the kernel's boot-time cleanup on ace) is whether a one-shot that does not linger has nothing running now: a declaration
 // that it be stopped is then satisfied, whatever it last did, because there is nothing to stop.
 func TestAOneShotIsReadByWhatItDid(t *testing.T) {
 	for _, c := range []struct {
 		name, show, want string
 		atRest           bool
 	}{
-		{"finished", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=0\n" +
-			"ExecMainStartTimestampMonotonic=5123456\n", "running", true},
-		{"finished, no timestamp read", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\n" +
-			"ExecMainStatus=0\n", "running", true},
-		{"failed", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=1\n" +
-			"ExecMainStartTimestampMonotonic=5123456\n", "stopped", true},
-		{"never ran", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=0\n" +
-			"ExecMainStartTimestampMonotonic=0\n", "stopped", true},
-		{"running now", "ActiveState=activating\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=0\n" +
-			"ExecMainStartTimestampMonotonic=5123456\n", "running", false},
+		{"finished", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=0\n",
+			"running", true},
+		{"failed", "ActiveState=inactive\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=1\n",
+			"stopped", true},
+		{"running now", "ActiveState=activating\nType=oneshot\nRemainAfterExit=no\nExecMainStatus=0\n",
+			"running", false},
 		{"lingers", "ActiveState=active\nType=oneshot\nRemainAfterExit=yes\nExecMainStatus=0\n",
 			"running", false},
 		{"a daemon, stopped", "ActiveState=inactive\nType=simple\nRemainAfterExit=no\nExecMainStatus=0\n",