Use readUniqueFileDescriptor in incidentd service

readFileDescriptor doesn't provide ownership of the fds. fdopen
needs ownership of the fds. Fds read from parcel should be duped
in this scenario and readUniqueFileDescriptor dups fds internally.

Test: m incidentd_service_fuzzer && adb sync data && adb shell /data/fuzz/x86_64/incidentd_service_fuzzer/incidentd_service_fuzzer
Test: atest incidentd_test
Bug: 286931110
Bug: 283699145

Merged-In: Ibe03a17dee91ac5bf25d123d4fd9c0bdd3c7d80e
Change-Id: Ibe03a17dee91ac5bf25d123d4fd9c0bdd3c7d80e
(cherry picked from commit ba78ef27)