ReadFileSymbolicLink checks /system/bin/ps

According to
https://android.googlesource.com/platform/build/+/refs/heads/android10-dev/core/Makefile#140,
/default.prop may not be a symbolic link.

Bug: 158552949
Test: atest CtsInitTestCases

Change-Id: I19bde577fa50280e1ed6fb8fdbe846655abb930b
Merged-In: I0d3f96c1656dfe02bfa0e801680f7fa887afd1d9
(cherry picked from commit 6f47feaccdbe849c982e0de9068e38be85006bfb)