fix accounts index startup stat and add two new stats for dups

[HaoranYi]

Problem

1. In accounts index startup stats, "total_item, max_bin_size, min_bin_size" are not populated. We are reading these stats too early - before the index are actually flushed. That's why they are all zeros. We should wait to read them after flush.

[2024-10-08T14:43:43.225032940Z
INFO
solana_metrics::metrics]
datapoint:
generate_index
overall_us=590639563i
total_us=505808369i
scan_stores_us=7810839i
insertion_time_us=67372816i
min_bin_size=0i
max_bin_size=0i
storage_size_storages_us=92035i
index_flush_us=424152i
total_rent_paying=0i
amount_to_top_off_rent=0i
total_items_including_duplicates=650345708i
total_items=0i
accounts_data_len_dedup_time_us=81218852i
total_duplicate_slot_keys=51300596i
populate_duplicate_keys_us=3019104i
total_slots=433370i
slots_to_clean=411148i

2. "total_item, max_bin_size, min_bin_size" actually represent the index items stored inside in-memory cache. Rename them to make it explicit that they are stats for in-memory index.

3. Add a stats to count how many dups (accounts_duplicates_num) and total_num_unique_duplicate_keys encountered during create account index at startup.

Summary of Changes

• fix account index startup stats
• add stats for dup account num at startup

[2024-10-08T20:12:36.127914984Z
INFO
solana_metrics::metrics]
datapoint:
generate_index
overall_us=145751031i
total_us=87320399i
scan_stores_us=1163008i
insertion_time_us=98630200i
min_bin_size_in_mem=989i
max_bin_size_in_mem=68834i
storage_size_storages_us=78822i
index_flush_us=525962i
total_rent_paying=0i
amount_to_top_off_rent=0i
total_items_including_duplicates=665224689i
total_items_in_mem=10070323i
accounts_data_len_dedup_time_us=55835509i
total_duplicate_slot_keys=52628546i
accounts_duplicates_num=42558223i
populate_duplicate_keys_us=1942864i
total_slots=418500i
slots_to_clean=418406i

Fixes #

[brooksprumo]

I think the code looks good. Some nits and requests to rename datapoints, since they are notoriously hard to change later.

[brooksprumo]

I kinda wish this was in a separate PR. So one PR for fixing the existing stats, and a second PR for adding the new stats.

[brooksprumo]

Looks good. I think this is correct.

[jeffwashington]

lgtm