qemu: Move qemuDomainSecretDestroy to qemuProcessLaunch

Rather than need to call qemuDomainSecretDestroy after any call to
qemuProcessLaunch, let's do the destroy in qemuProcessLaunch since
that's where command line is eventually generated and processed. Once
it's generated, we can clear out the secrets.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/qemu/qemu_process.c

@@ -5608,6 +5608,7 @@ qemuProcessLaunch(virConnectPtr conn,
     ret = 0;
 
  cleanup:
+    qemuDomainSecretDestroy(vm);
     virCommandFree(cmd);
     qemuDomainLogContextFree(logCtxt);
     virObjectUnref(cfg);
@@ -5720,8 +5721,6 @@ qemuProcessStart(virConnectPtr conn,
     }
     relabel = true;
 
-    qemuDomainSecretDestroy(vm);
-
     if (incoming &&
         incoming->deferredURI &&
         qemuMigrationRunIncoming(driver, vm, incoming->deferredURI, asyncJob) < 0)