Pass bucket list size to simulation as a side input. (stellar#1389)

### What

Pass bucket list size to simulation as a side input.

### Why

While it would be nice to encapsulate the computation logic based purely
on the ledger state, we don't currently emit the necessary meta to track
the respective config entry changes.

### Known limitations

N/A

soroban-simulation/src/network_config.rs

@@ -66,7 +66,10 @@ impl NetworkConfig {
     ///
     /// This may only fail in case when provided snapshot doesn't contain
     /// all the necessary entries or when these entries are mis-configured.
-    pub fn load_from_snapshot(snapshot: &impl SnapshotSourceWithArchive) -> Result<Self> {
+    pub fn load_from_snapshot(
+        snapshot: &impl SnapshotSourceWithArchive,
+        bucket_list_size: u64,
+    ) -> Result<Self> {
         let compute = load_setting!(snapshot, ContractComputeV0);
         let ledger_cost = load_setting!(snapshot, ContractLedgerCostV0);
         let historical_data = load_setting!(snapshot, ContractHistoricalDataV0);
@@ -76,26 +79,15 @@ impl NetworkConfig {
         let cpu_cost_params = load_setting!(snapshot, ContractCostParamsCpuInstructions);
         let memory_cost_params = load_setting!(snapshot, ContractCostParamsMemoryBytes);
 
-        let bucket_list_size_window = load_setting!(snapshot, BucketlistSizeWindow);
-        if bucket_list_size_window.is_empty() {
-            bail!("bucket list size window can not be empty");
-        }
-        let mut total_bucket_list_size: u128 = 0;
-        for s in bucket_list_size_window.iter() {
-            total_bucket_list_size = total_bucket_list_size.saturating_add(*s as u128);
-        }
-        let bucket_list_size: i64 = (total_bucket_list_size
-            / bucket_list_size_window.len() as u128)
-            .try_into()
-            .context("bucket list size is too large, the ledger is mis-configured")?;
-
         let write_fee_configuration = WriteFeeConfiguration {
             bucket_list_target_size_bytes: ledger_cost.bucket_list_target_size_bytes,
             write_fee_1kb_bucket_list_low: ledger_cost.write_fee1_kb_bucket_list_low,
             write_fee_1kb_bucket_list_high: ledger_cost.write_fee1_kb_bucket_list_high,
             bucket_list_write_fee_growth_factor: ledger_cost.bucket_list_write_fee_growth_factor,
         };
-
+        let bucket_list_size: i64 = bucket_list_size
+            .try_into()
+            .context("bucket list size exceeds i64::MAX")?;
         let write_fee_per_1kb =
             compute_write_fee_per_1kb(bucket_list_size, &write_fee_configuration);
 

soroban-simulation/src/test/network_config.rs

@@ -124,22 +124,13 @@ fn test_load_config_from_snapshot() {
             config_entry(ConfigSettingEntry::ContractCostParamsMemoryBytes(
                 memory_cost_params.clone(),
             )),
-            config_entry(ConfigSettingEntry::BucketlistSizeWindow(
-                vec![
-                    150_000_000_000_000 * 2,
-                    150_000_000_000_000,
-                    150_000_000_000_000 / 2,
-                    150_000_000_000_000 / 2,
-                ]
-                .try_into()
-                .unwrap(),
-            )),
         ],
         0,
     )
     .unwrap();
 
-    let network_config = NetworkConfig::load_from_snapshot(&snapshot_source).unwrap();
+    let network_config =
+        NetworkConfig::load_from_snapshot(&snapshot_source, 150_000_000_000_000).unwrap();
     // From tests/resources `test_compute_write_fee`
     let write_fee = 1_000_000_000 + 50 * (1_000_000_000_i64 - 1_000_000) / 2;
     assert_eq!(