Removed unsed DB and made source mandatory (#708)

## 📝 Summary

Removed flashbots DB from backtest sources.
Mempool source is not default and and now the source is mandaroty

## ✅ I have completed the following steps:

* [X] Run `make lint`
* [X] Run `make test`
* [ ] Added tests (if applicable)

Author: ZanCorDX

crates/rbuilder/src/backtest/fetch/backtest_fetch.rs

@@ -53,31 +53,24 @@ struct FetchCommand {
 
 pub async fn run_backtest_fetch<
     ConfigType: LiveBuilderConfig + Clone,
-    BundleSourceFactoryFut: Future<Output = eyre::Result<Option<Box<dyn DataSource>>>>,
-    BundleSourceFactoryType: FnOnce(ConfigType) -> BundleSourceFactoryFut,
+    OrderSourceFactoryFut: Future<Output = eyre::Result<Box<dyn DataSource>>>,
+    OrderSourceFactoryType: FnOnce(ConfigType) -> OrderSourceFactoryFut,
 >(
-    bundle_source_factory: BundleSourceFactoryType,
+    order_source_factory: OrderSourceFactoryType,
 ) -> eyre::Result<()> {
     let cli = Cli::parse();
     let config: ConfigType = load_config_toml_and_env(cli.config)?;
     config.base_config().setup_tracing_subscriber()?;
 
     match cli.command {
         Commands::Fetch(cli) => {
-            // create paths for backtest_fetch_mempool_data_dir (i.e "~/.rbuilder/mempool-data" and ".../transactions")
-            let backtest_fetch_mempool_data_dir =
-                config.base_config().backtest_fetch_mempool_data_dir()?;
-
             let provider = config.base_config().eth_rpc_provider()?;
             let mut fetcher = HistoricalDataFetcher::new(
                 provider,
                 config.base_config().backtest_fetch_eth_rpc_parallel,
-            )
-            .with_default_datasource(backtest_fetch_mempool_data_dir)?;
+            );
 
-            if let Some(bundle_source) = bundle_source_factory(config.clone()).await? {
-                fetcher = fetcher.with_datasource(bundle_source);
-            }
+            fetcher = fetcher.with_datasource(order_source_factory(config.clone()).await?);
 
             let blocks_to_fetch: Box<dyn Iterator<Item = u64>> = if cli.range {
                 let from_block = cli.blocks.first().copied().unwrap_or(0);