Db v4 fix metadata (clean)

[arienandalibi]

What changes were proposed in this pull request?

Fix .meta file not updating node and edge counts when the graph is flushed/dropped. Previously, these would stay 0.

Why are the changes needed?

Helps fix bugs in the UI.

Does this PR introduce any user-facing change? If yes is this documented?

It shouldn't.

How was this patch tested?

Some unit tests were added.

Are there any further changes required?

There shouldn't be.

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Rust Benchmark'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 2.

Benchmark suite	Current: 6258b50	Previous: 9823ef7	Ratio
lotr_graph/num_edges	4 ns/iter (± 0)	0 ns/iter (± 0)	+∞
lotr_graph/num_nodes	4 ns/iter (± 0)	1 ns/iter (± 0)	4
lotr_graph/has_node_nonexisting	5 ns/iter (± 0)	2 ns/iter (± 0)	2.50
lotr_graph/iterate_exploded_edges	609317 ns/iter (± 1487)	285473 ns/iter (± 2920)	2.13
lotr_graph/graph_latest	3 ns/iter (± 0)	0 ns/iter (± 0)	+∞
lotr_graph_materialise/materialize	7933711 ns/iter (± 15211)	1564816 ns/iter (± 35303)	5.07
lotr_graph_window_100/num_nodes	14 ns/iter (± 0)	5 ns/iter (± 0)	2.80
lotr_graph_window_100/iterate_exploded_edges	842137 ns/iter (± 11056)	325242 ns/iter (± 847)	2.59
lotr_graph_window_100_materialise/materialize	8408871 ns/iter (± 16324)	1669150 ns/iter (± 10700)	5.04
lotr_graph_window_10/has_node_existing	155 ns/iter (± 11)	62 ns/iter (± 11)	2.50
lotr_graph_window_10/iterate nodes	35031 ns/iter (± 906)	11339 ns/iter (± 40)	3.09
lotr_graph_window_10/iterate edges	102548 ns/iter (± 323)	48684 ns/iter (± 211)	2.11
lotr_graph_window_10/iterate_exploded_edges	454778 ns/iter (± 1846)	155788 ns/iter (± 1001)	2.92
lotr_graph_window_10_materialise/materialize	3607501 ns/iter (± 11265)	971980 ns/iter (± 4278)	3.71
lotr_graph_subgraph_10pc/has_node_nonexisting	5 ns/iter (± 0)	2 ns/iter (± 0)	2.50
lotr_graph_subgraph_10pc_materialise/materialize	1657703 ns/iter (± 21354)	334634 ns/iter (± 1287)	4.95
lotr_graph_subgraph_10pc_windowed/has_node_existing	161 ns/iter (± 10)	62 ns/iter (± 14)	2.60
lotr_graph_subgraph_10pc_windowed/iterate nodes	5585 ns/iter (± 93)	1365 ns/iter (± 3)	4.09
lotr_graph_subgraph_10pc_windowed_materialise/materialize	1027321 ns/iter (± 15458)	230399 ns/iter (± 2617)	4.46
lotr_graph_window_50_layered/num_edges	78365 ns/iter (± 2686)	38714 ns/iter (± 1017)	2.02
lotr_graph_window_50_layered/num_edges_temporal	163833 ns/iter (± 4111)	70121 ns/iter (± 7586)	2.34
lotr_graph_window_50_layered/num_nodes	43144 ns/iter (± 2394)	21435 ns/iter (± 536)	2.01
lotr_graph_window_50_layered/has_node_existing	450 ns/iter (± 22)	129 ns/iter (± 12)	3.49
lotr_graph_window_50_layered/has_node_nonexisting	5 ns/iter (± 0)	2 ns/iter (± 0)	2.50
lotr_graph_window_50_layered/iterate nodes	82847 ns/iter (± 208)	19308 ns/iter (± 47)	4.29
lotr_graph_window_50_layered/iterate edges	204213 ns/iter (± 431)	83616 ns/iter (± 1318)	2.44
lotr_graph_window_50_layered/graph_latest	82094 ns/iter (± 1767)	36649 ns/iter (± 916)	2.24
lotr_graph_window_50_layered_materialise/materialize	34035461 ns/iter (± 193231)	3488825 ns/iter (± 24948)	9.76
lotr_graph_persistent_window_50_layered/num_edges_temporal	676950 ns/iter (± 7245)	192686 ns/iter (± 1569)	3.51
lotr_graph_persistent_window_50_layered/has_node_existing	495 ns/iter (± 349)	174 ns/iter (± 83)	2.84
lotr_graph_persistent_window_50_layered/has_node_nonexisting	5 ns/iter (± 0)	2 ns/iter (± 0)	2.50
lotr_graph_persistent_window_50_layered/iterate nodes	108832 ns/iter (± 730)	35886 ns/iter (± 191)	3.03
lotr_graph_persistent_window_50_layered/iterate edges	189755 ns/iter (± 839)	84161 ns/iter (± 596)	2.25
lotr_graph_persistent_window_50_layered/iterate_exploded_edges	4844711 ns/iter (± 25305)	1659940 ns/iter (± 19402)	2.92
lotr_graph_persistent_window_50_layered/graph_latest	119831 ns/iter (± 1885)	57549 ns/iter (± 4809)	2.08
lotr_graph_persistent_window_50_layered_materialise/materialize	62289505 ns/iter (± 277851)	5298035 ns/iter (± 147912)	11.76
lotr_graph/proto_encode	9955324 ns/iter (± 105919)	1157897 ns/iter (± 73709)	8.60

This comment was automatically generated by workflow using github-action-benchmark.