system_server: remove CAP_SYS_MODULE

CAP_SYS_MODULE has been disabled by SELinux for over a decade now
(bug 7118228), and its continued presence in DAC policy is
causing misleading SELinux denials. Delete CAP_SYS_MODULE
from system_server.

Bug: 228030183
Test: Android compiles and boots
Flag: EXEMPT (already disallowed by SELinux policy. Code cleanup)
Change-Id: Ib48e1ae29ad2c28f89f9c5dcd882b2466ff82d3f