JobScheduler: Ignore important while foreground flag

Jobs with important while foreground flag set won't be relaxed by system
for doze restrictions any more.

Method JobInfo.isImportantWhileForeground() will always return false.

Bug: 374175032
Test: atest CtsJobSchedulerTestCases
Test: atest
    FrameworksMockingServicesTests: com.android.server.job.controllers.QuotaControllerTest
Flag: android.app.job.ignore_important_while_foreground
Change-Id: Ic11f2a106c1cd15c5e2d9842d8fffaf872022173