Remove stale nightly derivative config from regression-wally

[Copilot]

This PR addresses a review comment noting that bin/regression-wally still referenced way_4_4096_1024_rv64gc after it was removed from config/derivlist.txt. Without this update, nightly derivconfigtests could target a non-existent generated derivative config.

• Nightly deriv config alignment

  • Removed the obsolete way_4_4096_1024_rv64gc entry from derivconfigtests in bin/regression-wally.
  • Kept the rest of the nightly matrix unchanged.

• Scope

  • Single-line removal only, limited to the review-commented mismatch between derivative generation inputs and nightly regression config list.

# removed from derivconfigtests
["way_4_4096_1024_rv64gc", ["arch64i"]],