Removing unused big_clock_container

I couldn't find any other reference to it and removing code from NotificationPanelViewControler is always nice.
It ain't much, but it's honest work.

Bug: 201639277
Test: Presubmit
Change-Id: I0232c419cfac76efb135e69db7eb7f98b905fefa
Merged-In: I0232c419cfac76efb135e69db7eb7f98b905fefa
3 files changed