Currently we have python.REPL.enableShellIntegration. The upcoming change doesn't just apply to the "Python REPL" feature but to all terminals. So I would put it beside the other terminal settings like python.terminal.enableShellIntegration.

Also VS Code core has this as terminal.integrated.shellIntegration.enabled, we should use python.terminal.shellIntegration.enabled if we expect more settings related to shell integration, rather than just the single enablement.