SIMD-0550: Double disinflation rate

Not active on mainnet-beta; not active on testnet; not active on devnet.

Introduced in anza-xyz/agave PR #16499.

Feature id ddibiks7RHZR69QXYMCmk4EZNt6WckspTqEEWv6cS38.

Related

Vortex Testnet