pvf: use test-utils feature to export test only (#7538)

* pvf: use test-utils feature to export test only

* adding comment to test-utils feature

* make prepare-worker and execute-worker as optional dependencies and add comments to test-utils

* remove doc hidden from pvf testing

* add prepare worker and execute worker entrypoints to test-utils feature

* pvf: add sp_tracing as optional dependency of test-utils

* add test-utils for polkadot and malus

* add test-utils feature to prepare and execute workers script

* remove required features from prepare and executing

* Try to trigger CI again to fix broken jobs

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Co-authored-by: Marcin S <marcin@realemail.net>