fix(bb-sol): use cached solc in foundry config

[AztecBot]

Summary

• Fix barretenberg/sol/foundry.toml so solc = "../../l1-contracts/solc-0.8.30" is in profile.default, not under [fuzz].
• This makes forge test use the pre-downloaded l1-contracts-solc binary instead of falling back to SVM and fetching https://binaries.soliditylang.org/linux-amd64/list.json during test execution.

Investigation

• PR feat: merge-train/spartan-v5 #24053 was removed from merge queue by merge-group run 27607587707 on gh-readonly-queue/v5-next/pr-24053-bc61f8c0....
• The failing status was ci/x10-full, log http://ci.aztec-labs.com/1781601708617442.
• The concrete failed command was cd barretenberg/sol && forge test --no-match-contract Base, log http://ci.aztec-labs.com/422d1d46441daa4b.
• Failure was a DNS lookup while Forge attempted to fetch the Solidity compiler list from binaries.soliditylang.org.

Verification

• cd barretenberg/sol && forge config --json | jq -r '.profile.default.solc // .solc // "<unset>"' now prints ../../l1-contracts/solc-0.8.30.
• make l1-contracts-solc passes.
• make bb-sol passes.
• cd barretenberg/sol && forge test --no-match-contract Base passes: 168 tests passed, 0 failed.
• ./bootstrap.sh ci was attempted but this checkout has no ci command (Unknown command: ci).
• timeout 1800 ./bootstrap.sh ci-full-no-test-cache was attempted as the closest repo CI entrypoint, but the local container aborted in the test engine before reaching this change; targeted bb-sol verification above passed.

---

Created by claudebox · group: slackbot