[BR07.2] Redirect data saver switch to ConnectivityManager

This is no-op refactoring which redirect the method call
in NetworkManagementService from netd to ConnectivityService.

Test: atest FrameworksServicesTests:NetworkManagementServiceTest
Bug: 297836825
Change-Id: I90df4859730e354a8034f198c28226702e14a607
2 files changed