Use the same target SDK in ConnectivityCoverageTests and CTS.

Currently, ConnectivityCoverageTests is manually set to target
SDK 31. This is different from CtsNetTestCasesLatestSdk, and
CtsTetheringTestLatestSdk, which are set to 33 and 31
respectively. Set all of them to 33 via a defaults clause.

ConnectivityCoverageTests must have the same target SDK as CTS
because it includes many of the CTS tests (e.g., everything in
common/).

Bug: 236087258
Test: atest ConnectivityCoverageTests
Test: atest CtsNetTestCasesLatestSdk
Test: atest CtsTetheringTestLatestSdk
Change-Id: I88c16dc28d9b73557def25d7f669ed14ae9d360a