Ensure font loaded by PHASE_SYSTEM_SERVICES_READY

The previous code ensured font is loaded by the end of
PHASE_SYSTEM_SERVICES_READY for FontManagerService. This
change is a slight tweak to make sure font is loaded by the
time PHASE_SYSTEM_SERVICES_READY begins, so that any other
SystemService can access fonts during PHASE_SYSTEM_SERVICES_READY,
regardless of whether or not they hit PHASE_SYSTEM_SERVICES_READY
before/after FontManagerService.

Bug: 327941215
Change-Id: I20fb4411a8d3cc8ceb2f71c5cc1460cd55ccf2d6
Test: successful boot