Blob prices should not be used if parent chain doesn't return blob price

[amsanghi]

Fixes: NIT-3652

Ensures that blob prices are only used when the parent chain supports them.

Even if the config expected-surplus-gas-price-mode is set to BlobPrice, we now check whether the parent chain supports blobs by verifying that both header.BlobGasUsed and header.ExcessBlobGas are non-nil.

If either of these fields is nil (indicating lack of blob support), the logic falls back to the calldata price model.

This prevents incorrect behavior on chains that do not support EIP-4844.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 22.62%. Comparing base (7c81586) to head (68a1d20).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3450      +/-   ##
==========================================
+ Coverage   22.59%   22.62%   +0.02%     
==========================================
  Files         383      383              
  Lines       58047    58047              
==========================================
+ Hits        13118    13134      +16     
+ Misses      42905    42888      -17     
- Partials     2024     2025       +1     

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[joshuacolvin0]

LGTM