fs_config: remove empty fs_config_* automation.

The code to manage citing empty <partition>/etc/fs_config_{files|dirs}
content by specifically setting the file(s) to access mode 00000 is
bitrotted and ill-suited for multiple partitions and was written for
a more paranoid time when DAC and MAC rules were not nearly as mature.

Striking out the complications as it affected deterministic results.

Test: compile and boot
Bug: 119310326
Change-Id: Iec02e0c1194eaa799ab95adff4ff0951a24652a4