fix pre-dispatch PoV underweight for ParasInherent (#7378)

This should fix the error log related to PoV pre-dispatch weight being
lower than post-dispatch for `ParasInherent`:
```
ERROR tokio-runtime-worker runtime::frame-support: Post dispatch weight is greater than pre dispatch weight. Pre dispatch weight may underestimating the actual weight. Greater post dispatch weight components are ignored.
                                        Pre dispatch weight: Weight { ref_time: 47793353978, proof_size: 1019 },
                                        Post dispatch weight: Weight { ref_time: 5030321719, proof_size: 135395 }
```

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Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>