Test that file creation with default primary in lower case is allowed

Test that we are allowed to create files in top level directory in a
different case than standard default top level directory names defined
in Environment.java

Bug: 175809012
Test: atest
ScopedStorageDeviceTest#testInsertDefaultPrimaryCaseInsensitiveCheck

Change-Id: Ieef3b82a9310d01e18e990c1c7168c4f1ecb1944
Merged-In: Ieef3b82a9310d01e18e990c1c7168c4f1ecb1944