Clean up use of GetDalvikCache.

Switch the only caller of the non-void version of GetDalvikCache that set
create_if_absent true to use the void version of GetDalvikCache. Then no
callers of the non-void version of GetDalvikCache set create_if_absent to
true, so that argument is no longer needed. And without create_if_absent,
there is no case when the function will abort, so the 'OrDie" option is no
longer necessary.

Change-Id: I83f60dcc8a8f3b1f91fd2971e9028f6a7dd8384d
Test: m art-test-host
Test: m art-test-target