server_configurable_flags_data_file is used for storing server
configurable flags which have been reset during current booting.
system_server needs to read the data to perform related disaster
recovery actions.
For how the data is read, see SettingsToPropertiesMapper.java.

Test: build succeeds & manual on device
Change-Id: Ifa22aecc13af2c574579299d28433622abbe6b85