fix(rust/cardano-chain-follower): Fixing missing updating mithril stats with the new snapshot

[Mr-Leshiy]

Description

Fixed an issue of not updating a mithril stats when a new snapshot was downloaded.

Related Issue(s)

Related to input-output-hk/catalyst-voices#2950

Description of Changes

• Added a new new_live_total_blocks function, which updates only chain_stats.live.blocks stats
• Modified new_mithril_update, to update only mithril related stats.
• Fixed live_sync_backfill_and_purge, added missing new_mithril_update calls, to properly update mithril stats with the freshly downloaded snapshot.

Please confirm the following checks

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream module

[github-actions]

✅ Test Report | ${\color{lightgreen}Pass: 364/364}$ | ${\color{red}Fail: 0/364}$ |