Make account shrink configurable #17544 (#17778)

1. Added both options for measuring space usage using total accounts usage and for individual store shrink ratio using an enum. Validator CLI options: --accounts-shrink-optimize-total-space and --accounts-shrink-ratio
2. Added code for selecting candidates based on total usage in a separate function select_candidates_by_total_usage
3. Added unit tests for the new functions added
4. The default implementations is kept at 0.8 shrink ratio with --accounts-shrink-optimize-total-space set to true

Fixes #17544

runtime/src/snapshot_utils.rs

@@ -1,6 +1,6 @@
 use {
     crate::{
-        accounts_db::AccountsDb,
+        accounts_db::{AccountShrinkThreshold, AccountsDb},
         accounts_index::AccountSecondaryIndexes,
         bank::{Bank, BankSlotDelta, Builtins},
         bank_forks::ArchiveFormat,
@@ -605,6 +605,7 @@ pub fn bank_from_archive<P: AsRef<Path>>(
     account_indexes: AccountSecondaryIndexes,
     accounts_db_caching_enabled: bool,
     limit_load_slot_count_from_snapshot: Option<usize>,
+    shrink_ratio: AccountShrinkThreshold,
 ) -> Result<Bank> {
     let unpack_dir = tempfile::Builder::new()
         .prefix(TMP_SNAPSHOT_PREFIX)
@@ -636,6 +637,7 @@ pub fn bank_from_archive<P: AsRef<Path>>(
         account_indexes,
         accounts_db_caching_enabled,
         limit_load_slot_count_from_snapshot,
+        shrink_ratio,
     )?;
 
     if !bank.verify_snapshot_bank() {
@@ -796,6 +798,7 @@ fn rebuild_bank_from_snapshots(
     account_indexes: AccountSecondaryIndexes,
     accounts_db_caching_enabled: bool,
     limit_load_slot_count_from_snapshot: Option<usize>,
+    shrink_ratio: AccountShrinkThreshold,
 ) -> Result<Bank> {
     info!("snapshot version: {}", snapshot_version);
 
@@ -832,6 +835,7 @@ fn rebuild_bank_from_snapshots(
                 account_indexes,
                 accounts_db_caching_enabled,
                 limit_load_slot_count_from_snapshot,
+                shrink_ratio,
             ),
         }?)
     })?;