Remove string_number_conversions.h from payload_generation_config.cc am: 333a619cce am: bb9b5c4752

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3309079

Change-Id: I3e3220f0e295166da5c416a960ef93ca66a9a214
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>