Standardize on base::GetProperty in libgraphicsenv

GraphicsEnv.cpp used cutils to query some properties and libbase to
query others. Switch all of them to libbase which is compatible with
host.

Test: build, flash device, and open angle settings
Test: atest CtsAngleIntegrationHostTestCases
Change-Id: I2f96d88b22f2acea5ba8fbe59add38c90f7ff09e
Bug: 152620031