Remove mini-keyctl usage from UpdatableSystemFontTest

Bug: 313005703
Test: atest UpdatableFontDirTest UpdatableSystemFontTest
Test: atest GtsFontHostTestCases FontManagerTest
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:d5e936166beea5a5a2b37ce0d9b1795c0438a2d3)
Merged-In: Ib4a32a9bbb27ebd2e9a32dc308f79ec1c91332ce
Change-Id: Ib4a32a9bbb27ebd2e9a32dc308f79ec1c91332ce
1 file changed