chore: remove unneeded getsigners method from nft

[tac0turtle]

Description

there were no core logic changes. There was a migration to KVstoreservice and introduction of its own go.mod.

ref: #16663

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[tac0turtle]

so no tests run when you delete a file, something we should look into

[julienrbrt]

@Mergifyio backport release/v0.50.x

[mergify]

backport release/v0.50.x

✅ Backports have been created

• #16669 chore: remove unneeded getsigners method from nft (backport #16665) has been created for branch release/v0.50.x