[BUG] Running same app over a graph would causing project_to_simple triggered multiple times.

To reproduce:

```python
import graphscope as gs
from graphscope.dataset import load_modern_graph
g = load_modern_graph()
for i in range(5):
ret = gs.pagerank(g)
```

This could happen even if we project it at the beginning, cause it's still a property graph with 1 v label and 1 elabel. `_project_to_simple` will be called every time, thus makes performance degradation.

Start at gs.pagerank and trace the _project_to_simple call while reproducing the five-iteration example with load_modern_graph. Done means repeated pagerank calls do not trigger redundant projection work and avoid the reported performance degradation.

Written by the indexing model from the issue text.