Defer low priority jobs in poor network conditions.

A poor network connection typically means it takes more power to
transmit data and the device will heat up quickly trying to transmit
data. In a poor network scenario, we should try to only use the network
for important work, so defer low priority jobs on poorer network
connections.

Bug: 210077394
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/job
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/job
Test: atest CtsJobSchedulerTestCases
Change-Id: I33f2daac404ef2c399c58364e4c214152cc47de0