Update logging line to add client_count in DisplayEventCallbackOccurred atom

To log number of unique clients that received the event.

Bug: 433483856
Flag: com.android.server.display.feature.flags.enable_logging_for_display_events
Test: atest DisplayServiceTests
Test: atest DisplayFrameworkStatsLoggerTest
Change-Id: Ic3214257261aa5cf49515f61c30d894e2e600a1a
2 files changed