remove the old token metadata processor

[rafaelcr]

now that we have the Token Metadata API in place and that we are redirecting all FT metadata endpoints to it, we should get rid of the token metadata processor completely

[rafaelcr]

we should, however, make sure we do not disrupt Rosetta's functionality when returning token operations (symbol, decimals, etc.)

[rafaelcr]

For Rosetta, we could fetch token contract decimals and symbols using read-only contract calls that follow SIP-010 (get-decimals, get-symbol) and use an in-memory cache for performance optimization

[smcclellan]

@rafaelcr Given that we can't get rid of this processor completely, is this still worth doing?