Properly flush unique queues on startup (#23154)

There have been a number of reports of PRs being blocked whilst being
checked which have been difficult to debug. In investigating #23050 I
have realised that whilst the Warn there is somewhat of a miscall there
was a real bug in the way that the LevelUniqueQueue was being restored
on start-up of the PersistableChannelUniqueQueue.

Next there is a conflict in the setting of the internal leveldb queue
name - This wasn't being set so it was being overridden by other unique
queues.

This PR fixes these bugs and adds a testcase.

Thanks to @brechtvl  for noticing the second issue.

Fix #23050
and others

---------

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/queue/queue_disk_channel_test.go

@@ -39,7 +39,7 @@ func TestPersistableChannelQueue(t *testing.T) {
 		Workers:      1,
 		BoostWorkers: 0,
 		MaxWorkers:   10,
-		Name:         "first",
+		Name:         "test-queue",
 	}, &testData{})
 	assert.NoError(t, err)
 
@@ -135,7 +135,7 @@ func TestPersistableChannelQueue(t *testing.T) {
 		Workers:      1,
 		BoostWorkers: 0,
 		MaxWorkers:   10,
-		Name:         "second",
+		Name:         "test-queue",
 	}, &testData{})
 	assert.NoError(t, err)
 
@@ -227,7 +227,7 @@ func TestPersistableChannelQueue_Pause(t *testing.T) {
 		Workers:      1,
 		BoostWorkers: 0,
 		MaxWorkers:   10,
-		Name:         "first",
+		Name:         "test-queue",
 	}, &testData{})
 	assert.NoError(t, err)
 
@@ -433,7 +433,7 @@ func TestPersistableChannelQueue_Pause(t *testing.T) {
 		Workers:      1,
 		BoostWorkers: 0,
 		MaxWorkers:   10,
-		Name:         "second",
+		Name:         "test-queue",
 	}, &testData{})
 	assert.NoError(t, err)
 	pausable, ok = queue.(Pausable)