Roll engine to 09ff9493e08c0c937bcd2c6f780981e2a7c5f2b5.

09ff9493e Re-land removal of vmservice_io from release builds. (#5784)
b523ee847 Revert "Switch to Fuchsia's ICU (#5774)" (#5801)
69695493b Switch to Fuchsia's ICU (#5774)