@JvmSerializableLambda was used in NetworkAgentTest to get around the
link error caused by JUnit enumerating through lambda methods that
referenced classes that weren't available on older platform versions.
Since this code was ported from NetworkAgentTest to CarrierConfigRule
whose lambda methods are not enumerated by JUnit, this workaround isn't
necessary anymore.
Flag: EXEMPT test only change
Bug: 409710349
Test: atest TetheringManagerTest
Change-Id: Ib876e237b239661548ae3c1d23fcb52f389f6254
5db5a47144