fix: use G1 generator from SRS

[ivokub]

Description

In #949 we optimized in KZG folding to use curve basepoint to evaluate foldedEval, but KZG SRS G1 generator may be different. This PR reverts the change.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How has this been tested?

Tests work downstream in Linea prover.

How has this been benchmarked?

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I did not modify files generated from templates
• golangci-lint does not output errors locally
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules