Clean up pre-revamped UI sections (2/3)

Remove files no longer needed in revamped UI that are related to section
views and controllers. This is a part of the effort to clean up
pre-revamped UI files and eventually remove the revamped UI flag.

Bug: 262780002
Test: manually verified that functionalities throughout the revamped UI
picker still work

Change-Id: Iaa39a51dad58106a3123d5b578934c058cd6df44