Fix GPU failures (#1881)

[vfdev-5]

Original PR #1881

Check list:

• New tests are added (if a new feature is added)
• New doc strings: description and/or example code are in RST format
• Documentation is updated (if required)

[vfdev-5]

@KickItLikeShika if tests are passing here, let's apply the same trick to other tests of median related metrics.

[KickItLikeShika]

@vfdev-5 unfortunately it didn't work..

[KickItLikeShika]

I found the error! we did np_res_prepend = 100.0 * np.median(e) but it should be np_res_prepend = 100.0 * np.median(e_prepend).
I will send a follow up PR to fix that

[KickItLikeShika]

@vfdev-5 It works fine now, thanks for providing such inspiring ideas! Thanks for your help!