Update responsive grid spec cell size remainderSpace logic

Refactoring the cellSize spec of responsive grid to divide the remainder space in code instead of dividing by cols/rows in the spec definition. For example, instead of using 0.2 in the spec for 5x5 grid (1 / number of rows), it is going to use 1 (100% of the remainder space) and divide the percentage by the number of cols or rows in code.

Fix: 313621277
Flag: ACONFIG com.android.launcher3.enable_responsive_workspace TEAMFOOD
Test: NexusLauncherImageTests
Test: CalculatedWorkspaceSpecTest
Test: DeviceProfileDumpTest
Test: DeviceProfileAlternativeDisplaysDumpTest
Change-Id: Ifaec838ac9751562ecedc1fe39b966ee3d092de3