Proto: differentiated inactivity tolerance

Depends on !18946 (merged)

The following will be done in another MRs:

• update the documentation on octez.tezos.com
• add more tests

What

https://docs.google.com/document/d/1iMSWLJOfOBTRy7wuJvaKkUJIrawQpUzwauMeJ4y9csw/edit?tab=t.0#heading=h.oeumxcgkpsfk

How

The parametric constant tolerated_inactivity_period is replaced by three constants:

• tolerated_inactivity_period_low: low period length (in cycles), for baker for which we have a lowest tolerance because their share of the stake is above the threshold
• tolerated_inactivity_period_high: high period length (in cycles), for baker for which we have a highest tolerance because their share of the stake is below the threshold
• tolerated_inactivity_period_threshold: staking ratio threshold, in per thousand

At the time we update the deactivation cycle, we look at the staking rights distribution used for the current cycle, and choose the tolerance accordingly.

For a delegate that registers, we initially set a low tolerance (plus the usual consensus_rights_delay) as we have no selected staking rights to look at.

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR