Remove obsolete storage items.

[shamil-gadelshin]

Description

Remove obsolete storage items from the blockchain state:

• LastHotkeyColdkeyEmissionOnNetuid
• SubnetAlphaEmissionSell
• NetworkMinAllowedUids
• NeuronsToPruneAtNextEpoch
• DynamicBlock (migrate_rao)
• TotalStakeAtDynamic (migrate_rao, do_register_network)
• SubnetName (get_name_for_subnet)

These storage items were removed; related migrations and migration tests were added as well. Only two items have entries: DynamicBlock(value) and TotalStakeAtDynamic (96 items = 4KB). All storage types (value, map, double map) are treated as raw DB items using a single template method.

Related Issue(s)

• Closes Investigate unused storage items within pallet-subtensor. #1557

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe):

Breaking Change

All dependent applications must be reworked.

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have run cargo fmt and cargo clippy to ensure my code is formatted and linted correctly
• 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 modules

[github-actions]

@opentensor/cerebrum / @opentensor/gyrus / @opentensor/cortex breaking change detected! Please prepare accordingly!