delete contents of the storage folder instead of the entire folde

[iCollin]

This PR is ready for review.

Summary

Change removal of the storage folder to actually remove storage folder contents.

This is needed because in our parallel atf runner, I recently added a ramdisk mount at core's storage folder to ease the stress on disk. Now Core's backup thread will be writing to RAM instead of disk making the whole system faster. This causes one test to fail: ./test_scripts/CloudAppRPCs/010_get_icon_url.lua because it cannot delete a folder that is a mount. This PR will enable all tests to pass with storage as a ramdisk.

ATF version

latest

Changelog

Enhancements

• core's storage folder can be a mount

CLA

• I have signed the CLA

[dboltovskyi]

@iCollin Please notice there are few more places where storage folder is removed completely:

• sdl_atf_test_scripts/test_scripts/API/SetAppIcon/commonIconResumed.lua

  Line 189 in c3b171d

  function m.preconditions()

• sdl_atf_test_scripts/test_scripts/API/SubMenuIcon/commonSubMenuIcon.lua

  Line 92 in c3b171d

  function m.preconditions()

• sdl_atf_test_scripts/test_scripts/SDL5_0/TTSChunks/common.lua

  Line 26 in c3b171d

  function m.preconditions()

• sdl_atf_test_scripts/user_modules/shared_testcases/testCasesForExternalUCS.lua

  Line 60 in c3b171d

  function m.removeLPT()

Besides these ones which are used in regression test pack, there are also a few other ones which are not supported, e.g.:

• sdl_atf_test_scripts/test_scripts/smoke_api.lua

  Line 19 in c3b171d

  os.execute("rm -rf " .. appStorageFolder)

[iCollin]

@dboltovskyi thank you for noticing, I have accommodated all places I could find removing the storage folder in tests that our team uses, and added an assert to the rm calls. There are many other references to the storage folder in legacy tests that I have not updated.