Respect SkipPresubmit annotation for ConnectivityCoverageTests

Follow-up from aosp/2788197, the CL does not work since
SkipPresubmit annotation is not excluded from TEST_MAPPING for
ConnectivityCoverageTests.

Test: TH
Bug: 302325928
Change-Id: I2d953f19e5d5eb5f5d8fdf4faf335d603bae42a0