Fix performance regression of system_server boot time

The hash calculation of FontFamily took a time. In this case, just
using identity hash should be fine.

Bug: 263015762
Test: atest TypefaceSystemFallbackTest FontListParserTest
Test: atest UpdatableFontDirTest UpdatableSystemFontTest
Test: atest FontManagerTest
Change-Id: Id8c39e646f92977867c82a1effb93c925c909ef2
1 file changed