Upgrade Rust to 1.89.0

[steviez]

Problem

We have been stuck on Rust 1.86.0 for a while due to an observed performance regression:

• See Downgrade Rust to 1.86.0 #6980 for initial observation of regression (and revert from 1.87 to 1.86)
• See PoH Performance degradation with rust 1.87+ #8869 for investigation into the actual underlying issue

As identified in #8869, we have a path forward that will allow us to upgrade without suffering an intermediate performance regression. Namely, land a patch in solana-sdk and advance straight to Rust 1.89.0. #8869 (comment) discusses a BP that makes 1.88 stable viable, but 1.88 nightly is still susceptible to the regression so it is probably best to advance to 1.89 to avoid wasting any more developer time on this

Proposed Solution

Do the following steps in order:

• Merge the patch in solana-sdk (Fix hasher performance degredation caused by rust upgrade solana-sdk#426)
• Push a new tag (v3.0.1) of solana-sha256-hasher
• Upgrade solana-sha256-hasher in agave (chore: Bump solana-sha256-hasher from 3.0.0 to 3.0.1 #8904)
• PR(s) for clippy lints / compilation failures / etc to advance us from 1.86 ==> 1.89
  • 1.87 lints should have been resolved per Upgrade Rust to 1.87.0 #6279
  • 1.88 lints should have been resolved per Resolve clippy lints blocking rust upgrade to 1.88.0 #6850
  • It is possible that new code has been added that violates new lints and will need to be addressed
• Update Rust to 1.89.0 #8892
  • Just multiple versions in one PR to avoid intermediate regression
• Communicate team to keep a close eye on metrics
  • Discord link

[steviez]

The 1.89 upgrade PR has landed, and all TODO items are done & updated with any links for tracking. So, we're done here