Fix job readiness checking.

Only mark dynamic constraints as satisfied if there are any dynamic
constraints specified, otherwise, JS will bypass the quota check and
always consider jobs without dynamic constraints as ready.

Bug: 151274168
Test: atest CtsJobSchedulerTestCases
Test: atest QuotaControllerTest
Change-Id: Ie70c8b1ae138eb063af981ae2b248b1a0bdbdc60