Remove dead code in pallet-subtensor

[ales-otf]

Description

Removes dead methods and types listed below.

Methods:

• get_normalized_stake
• get_number_of_subnets
• get_total_hotkey_delegated_stake
• get_validator_prune_len
• has_axon_info
• has_prometheus_info
• is_registration_allowed Remove dead code in pallet-subtensor #1036 (comment)
• passes_rate_limit_globally
• set_balance_on_coldkey_account
• set_last_tx_block_childkey_take

Error variants:

• NewColdKeyIsSameWithOld
• ColdKeySwapTxRateLimitExceeded
• NotExistColdkey
• NoBalanceToTransfer
• SameColdkey
• DuplicateColdkey
• ColdkeySwapError
• InsufficientBalanceToPerformColdkeySwap
• MaxColdkeyDestinationsReached
• SwapColdkeyOnlyCallableByRoot
• NewColdkeyIsInArbitration

Related Issue(s)

• Closes Clean up/refactor Pallet type from the Subtensor module #983

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):

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