Add NetworkProviderTest#testRegisterNetworkOffer back into test

This test was temporarily disabled because prebuilt module is not
updated in the branch. Now the prebuilt was S already, so add the
test back to test to ensure the coverage.

Test: atest FrameworksNetTests CtsNetTestCases
Bug: 189074532
Change-Id: I510f457d2869c2904404fe7ef55828e84636e4c5
1 file changed