Remove "result2" in AccountManagerService

I think result2 here is to filter out other value returned from getAccountRemovalAllowed.
As the annotation shown in getAccountRemovalAllowed in AbstractAccountAuthenticator,
the result will only contain KEY_INTENT or KEY_BOOLEAN_RESULT or
KEY_ERROR_CODE and KEY_ERROR_MESSAGE. KEY_INTENT has been judged at the beginning of onResult,
KEY_ERROR_CODE and KEY_ERROR_MESSAGE seem extraneous when back to AccountManager,
so i believe that it's ok to use result directly here other than get one more Bundle object.
(tip: if result2 is nessesary, its name doesn't looks formal)

Bug:N/A
Test:N/A

Change-Id: I4e352baa1e74ac680398c328db0c4bc873ba528b
Signed-off-by: tiansiming <tiansiming@xiaomi.com>