statement-store performance benchmarks (paritytech#9763)

# Description

Adds benchmarks to measure the performance of the statement-store:
- Message Exchange Scenario: interaction with one or many nodes.
- Memory Stress Test Scenario.

## Results

**Key improvements made to improve the performance:**
- [Fixed a
deadlock](paritytech#9868)
- [Increased statements
limits](paritytech#9894)
- [Improved
gossiping](paritytech#9912)

**Hardware**
All benchmarks were run on a MacBook Pro M2

### 1. Message Exchange Scenario
**Test Configuration**
- Total participants: 49_998
- Group size: 6 participants per group
- Total groups: 8_333
- Statement payload size: 512 KB
- Propagation delay: 2 seconds (empirically determined)
- Parachain network tested with: 2, 3, 6, 12 nodes

**Network Topologies**
We tested two distribution patterns:
1. **To one RPC:** All participants send statements to a single RPC node
2. **To all RPC:** Participants distribute statements across all nodes
(slower due to gossiping overhead)

**Participant Flow**
- Sends a statement with their key for an exchange session (1 sent)
- Waits 2 seconds for statement propagation
- Receives session keys from other members in the group (5 received)
- Sends statements containing a 512KB message to each member in the
group (5 sent)
- Waits 2 seconds for statement propagation
- Receives messages from other members (5 received)
- Total: 6 sent, 10 received.


**Results**

| Collators      | Avg time | Max time | Memory |
| -------------- | -------- | -------- | ------ |
| **To one RPC** |          |          |        |
| 2              | 35s      | 35s      | 2.1GB  |
| 6              | 48s      | 50s      | 1.7GB  |
| **To all RPC** |          |          |        |
| 3              | 41s      | 51s      | 1.9GB  |
| 6              | 61s      | 71s      | 1.4GB  |
| 12             | 94s      | 119s     | 1.9GB  |

**Observations**
- Sending to one RPC node is faster but creates a bottleneck
- Distributing across all nodes takes longer due to gossiping overhead
- More collators increase gossiping load, resulting in slower completion
times
- Memory usage per node remains around 2GB.


### 2. Memory Stress Test Scenario

**Test Configuration**
We prepared one more scenario to check how much memory nodes use with a
full store after we increased the limits. To maximize memory usage for
index usage, we submitted statements with all unique topics; other
fields (e.g., proofs) were not used.
- Total tasks: 100,000 concurrent
- Statement size: 1 KB per statement
- Network size: 6 collators

**Test Flow**
1. Spawn 100,000 concurrent tasks
2. Each task sends statements with 1KB payload to one node until store
is full
3. Statements are gossiped across the network to the other 5 collators
4. Test completes when all collator stores are full

**Results**
During the tests, each node used up to 4.5GB of memory.

Author: AndreiEres

Cargo.lock

@@ -21,8 +21,10 @@ zombienet-orchestrator = { workspace = true }
 zombienet-configuration = { workspace = true }
 cumulus-zombienet-sdk-helpers = { workspace = true }
 sp-statement-store = { workspace = true, default-features = true }
+sc-statement-store = { workspace = true, default-features = true }
 sp-keyring = { workspace = true, default-features = true }
 sp-core = { workspace = true, default-features = true }
+codec = { workspace = true }
 rstest = { workspace = true }
 
 [features]

cumulus/zombienet/zombienet-sdk/Cargo.toml

@@ -11,4 +11,5 @@ mod pov_recovery;
 mod rpc_collator_build_blocks;
 mod runtime_upgrade;
 mod statement_store;
+mod statement_store_bench;
 mod sync_blocks;