Fix metrics backwards compatibility

[teddykoker]

Moved to pl.metrics.utils (some users have complained about this)

TODO: add function back to functional (with deprecation warning) that simply calls new one

[Borda]

it just about importing, so the fix is add in functional __init__ corrected in #5062

[edenlightning]

@teddykoker @Borda can we close this?

[Borda]

@teddykoker @Borda can we close this?

it is in #5067