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.go

@@ -217,16 +217,12 @@ func (arch) ServiceState(ctx context.Context, run Runner, unit string) (string,
 	//
 	// So for that shape, what "running" means is "it ran, and it worked".
 	//
-	// **And one that never ran is not one that worked** (novox/hq issue 1126). systemd says
-	// ExecMainStatus=0 for a unit that has not run since the manager loaded it exactly as for one
-	// that succeeded; only its start timestamp, 0, separates them. Read as "running", a package's
-	// boot-time one-shot declared stopped could never be satisfied — stopping an inactive unit
-	// changes nothing, and the read back said running again — and one declared running was never
-	// started. A timestamp the manager did not say keeps the reading it had before.
+	// It cannot be told from one that never ran: systemd says ExecMainStatus=0 and a start timestamp
+	// of 0 for a one-shot that never ran, and also for one that ran and was unloaded because nothing
+	// referenced it, then loaded again. So a one-shot declared running that must be seen to have run
+	// lingers (RemainAfterExit) or is enabled at boot; one declared stopped is judged at rest by the
+	// apply (ServiceAtRest, novox/hq issue 1126).
 	if u.oneShotAtRest() {
-		if u.started == "0" {
-			return "stopped", nil
-		}
 		if u.exited == "0" || u.exited == "" {
 			return "running", nil
 		}
@@ -259,7 +255,7 @@ func (arch) ServiceAtRest(ctx context.Context, run Runner, unit string) (bool, e
 
 // shownUnit is what `systemctl show` says of a unit, as far as its state is read.
 type shownUnit struct {
-	load, active, kind, remains, exited, started string
+	load, active, kind, remains, exited string
 }
 
 // oneShotAtRest is a one-shot that does not linger and is not running now.
@@ -273,8 +269,7 @@ func (u shownUnit) oneShotAtRest() bool {
 func showUnit(ctx context.Context, run Runner, unit string) (shownUnit, error) {
 	out, asked := run(ctx, "systemctl", "show",
 		"--property=LoadState", "--property=ActiveState", "--property=Type",
-		"--property=RemainAfterExit", "--property=ExecMainStatus",
-		"--property=ExecMainStartTimestampMonotonic", "--", unit)
+		"--property=RemainAfterExit", "--property=ExecMainStatus", "--", unit)
 	var u shownUnit
 	for _, line := range strings.Split(out, "\n") {
 		key, value, found := strings.Cut(strings.TrimSpace(line), "=")
@@ -292,8 +287,6 @@ func showUnit(ctx context.Context, run Runner, unit string) (shownUnit, error) {
 			u.remains = value
 		case "ExecMainStatus":
 			u.exited = value
-		case "ExecMainStartTimestampMonotonic":
-			u.started = value
 		}
 	}
 	if u.load == "" {