Fix ojluni testng.xml

The file contained an invalid class name.

Bug: 69541902
Test: Manually checked that after running:
    art/tools/buildbot-build.sh --host && make core-ojtests-hostdex
  the following crashes before but not after this CL:
    libcore/ojluni/src/test/artrun-testng
  Specifically, before this CL, it fails with:
    Cannot find class in classpath: test.java.time.chrono;
  Note: It wasn't obvious which dependencies were required; the
  BOOT_DEXJARS from ojluni/src/test/artrun don't seem to have been
  enough.

Change-Id: I1c350808054863f2d1fe6dbd79befc24c46fd7a4