Schedule a maintenance job to clean up stale jobs.

+ Fix a bug in BlobMetadata.hasLeases().

Bug: 148754858
Test: atest ./services/tests/mockingservicestests/src/com/android/server/blob/BlobStoreManagerServiceTest.java
Test: adb shell cmd jobscheduler run --force android 191934935
Change-Id: I13499dd0327414bee62b8395c7e1fd349e325dd4