refactor(storage): make indexes non-nullable

[glevco]

Depends on #1542

Motivation

Previous PR #1542 removed the cache storage, which was the only reason IndexesManager was nullable in the transaction storage. This PR addresses this, simplifying code, as it doesn't have to be nullable anymore. The MempoolTipsIndex is also required, but code unnecessarily treated it as optional.

Acceptance Criteria

• Make IndexesManager non-nullable in the TransactionStorage.
  • Remove all the indexes is not None and not_none(indexes) assertions.
• Make MempoolTipsIndex non-nullable in the IndexesManager.
  • Remove all the mempool_tips is not None and not_none(mempool_tips) assertions.
• Remove some methods that are not necessary anymore: enable_mempool_index, force_clear_all, reset_indexes, and the _saving_genesis attribute.

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.29%. Comparing base (42aa09a) to head (88f1696).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1543      +/-   ##
==========================================
+ Coverage   86.27%   86.29%   +0.02%     
==========================================
  Files         437      437              
  Lines       33708    33605     -103     
  Branches     5260     5247      -13     
==========================================
- Hits        29080    29001      -79     
+ Misses       3611     3599      -12     
+ Partials     1017     1005      -12     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

The base branch was changed.

[github-actions]

Bencher Report

Branch	refactor/require-indexes
Testbed	ubuntu-22.04

🚨 1 Alert

Benchmark	Measure Units	View	Benchmark Result (Result Δ%)	Lower Boundary (Limit %)
sync-v2 (up to 20000 blocks)	Latency minutes (m)	📈 plot 🚷 threshold 🚨 alert (🔔)	1.36 m (-20.86%) Baseline: 1.72 m	1.55 m (113.72%)

Click to view all benchmark results

Benchmark	Latency	Benchmark Result minutes (m) (Result Δ%)	Lower Boundary minutes (m) (Limit %)	Upper Boundary minutes (m) (Limit %)
sync-v2 (up to 20000 blocks)	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	1.36 m (-20.86%) Baseline: 1.72 m	1.55 m (113.72%)	2.06 m (65.95%)

🐰 View full continuous benchmarking report in Bencher