revert: P256VerifyGas to 3450

[kamuikatsurgi]

Description

Bor's implementation was based on EIP-7212 (the original P256 precompile proposal) with a gas cost of 3450, while upstream go-ethereum implemented EIP-7951 (a newer revision) with a gas cost of 6900.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.57%. Comparing base (ed902e3) to head (bec09e4).

Files with missing lines	Patch %	Lines
core/vm/contracts.go	0.00%	2 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (0.00%) is below the target coverage (90.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2030      +/-   ##
===========================================
- Coverage    49.59%   49.57%   -0.03%     
===========================================
  Files          874      874              
  Lines       150517   150520       +3     
===========================================
- Hits         74652    74618      -34     
- Misses       70837    70865      +28     
- Partials      5028     5037       +9     

Files with missing lines	Coverage Δ
params/protocol_params.go	84.21% <ø> (ø)
core/vm/contracts.go	74.94% <0.00%> (-0.27%)	⬇️

... and 19 files with indirect coverage changes

Files with missing lines	Coverage Δ
params/protocol_params.go	84.21% <ø> (ø)
core/vm/contracts.go	74.94% <0.00%> (-0.27%)	⬇️

... and 19 files with indirect coverage changes

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