Simplify deleting startup dex cache arrays.

- No need to be in a GC critical section.
- Make sure the dex cache is in the expected state before registering
  it.

Also remove now unused ScopedInterruptibleGCCriticalSection

Test: test.py
Change-Id: I27b1209c7a21b811f9e17677e5e2bf70456aad8c
7 files changed