[netd] fix deprecation warning

Fixes:
//system/netd/server:netd_unit_test clang-tidy IptablesRestoreControllerTest.cpp
/android0/aosp/system/netd/server/IptablesRestoreControllerTest.cpp:58:15:
warning: Google Test APIs named with 'case' are deprecated; use
equivalent APIs named with 'suite' [google-upgrade-googletest-case]
  static void SetUpTestCase() {
              ^~~~~~~~~~~~~
              SetUpTestSuite

Test: mm
Change-Id: Idfbc436cf15a96879165266edc51a5d6f45bd1c6