Fixed clock face resetting to default one after rebooting

The root cause is that the initial clock plugin was set before the onPluginConnected() was
called.

Set the clock plugin once the onPluginConnected() is called and it's
current clock plugin.

Bug: 131044332
Test: manual
Change-Id: I133183d66db05620d6da77abb0643e8e5ee60ebc