Fix content holes in Actions task logs file (#25560)

Fix #25451.

Bugfixes:
- When stopping the zombie or endless tasks, set `LogInStorage` to true
after transferring the file to storage. It was missing, it could write
to a nonexistent file in DBFS because `LogInStorage` was false.
- Always update `ActionTask.Updated` when there's a new state reported
by the runner, even if there's no change. This is to avoid the task
being judged as a zombie task.

Enhancement:
- Support `Stat()` for DBFS file.
- `WriteLogs` refuses to write if it could result in content holes.

---------

Co-authored-by: Giteabot <teabot@gitea.io>

models/dbfs/dbfs_test.go

@@ -111,6 +111,19 @@ func TestDbfsBasic(t *testing.T) {
 
 	_, err = OpenFile(db.DefaultContext, "test2.txt", os.O_RDONLY)
 	assert.Error(t, err)
+
+	// test stat
+	f, err = OpenFile(db.DefaultContext, "test/test.txt", os.O_RDWR|os.O_CREATE)
+	assert.NoError(t, err)
+	stat, err := f.Stat()
+	assert.NoError(t, err)
+	assert.EqualValues(t, "test.txt", stat.Name())
+	assert.EqualValues(t, 0, stat.Size())
+	_, err = f.Write([]byte("0123456789"))
+	assert.NoError(t, err)
+	stat, err = f.Stat()
+	assert.NoError(t, err)
+	assert.EqualValues(t, 10, stat.Size())
 }
 
 func TestDbfsReadWrite(t *testing.T) {