Potential improvements to the release/verify rc scripts

[kevinjqliu]

Potential improvements to the release/verify rc scripts

• RC verification script should download artifacts from the apache repo, https://github.com/apache/iceberg-go/blob/main/dev/release/verify_rc.sh#L38 should reference https://dist.apache.org/repos/dist/dev/iceberg/ instead of GitHub
  • Fixed verify_rc.sh, download artifacts from apache dist #205
• (from JB on devlist) "sha256 is not required anymore, sha512 is enough"
  • Fixed by ci(infra): Remove sha256 #226
• release_rc.sh should upload artifact to https://dist.apache.org/repos/dist/dev/iceberg/ and should follow this structure
• fix release_rc to generate .asc file

[chil-pavn]

Hi @kevinjqliu i would like to take up the unchecked items.