Disable two line text legacy flag.

Will now repurpose the twolinetoggle flag to be the flag that will
make twoline text enabled/disabled.

bug: 316027081
Test: presubmit
manually: https://screenshot.googleplex.com/BsZGCm7DrTZLwG4
Flag: com.android.launcher3.enable_twoline_toggle Staging
Merged-In: Idef427bad6551ae56b13e35393e076b8e000af5a
Change-Id: Idef427bad6551ae56b13e35393e076b8e000af5a