Stop using factory serial numbers in NetworkFactory.

Don't delete NetworkFactory.SerialNumber or getSerialNumber() yet
because those are still in use in various places.

Test: builds
Bug: 138306002
Change-Id: I102af09cb52b447e472398869d82556b5708cb82
Merged-In: I102af09cb52b447e472398869d82556b5708cb82
1 file changed