Include all sn owner hotkeys in burn keys

[gztensor]

Description

We currently burn alpha of subnet owner hotkey ("burn key"). This PR includes all subnet owner hotkeys in burn keys.

let subnet_owner_coldkey = SubnetOwner::<T>::get(netuid);
let hotkey_owner = Owner::<T>::get(&hotkey);
if hotkey_owner == subnet_owner_coldkey {
    burn = true;
}

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