Remove temporary fix for secp192 curves in `test_psa_crypto_without_heap`

[valeriosetti]

Suggested enhancement

Just remove these 2 lines (and the comment above) from test_psa_crypto_without_heap:

    scripts/config.py set PSA_WANT_ECC_SECP_K1_192 || true
    scripts/config.py set PSA_WANT_ECC_SECP_R1_192 || true

The fix was introduced in #10519. It won't be anymore required once Mbed-TLS/TF-PSA-Crypto#570 is merged.

Justification

Mbed TLS needs this because we want to keep test code clean