fix(verify-release): fix bash pipe FD leak causing deadlock on maven checksum verification

[adnanhemani]

Without this fix, the verify script deadlocks and stalls past a amount of artifacts processed during the Maven Repo Signature and Checksum Verification:

As I am no expert at this, I am relying on Claude's explanation that the process substitution used earlier doesn't close the pipe FDs reliably, which eventually ends up in a deadlock. The new code eliminates pipes altogether and therefore has nothing to leak.

If anyone has a better way of doing this, please suggest to raise a different PR - I am only going with this as this suggestion worked for me, but unsure if it is the correct long-term fix.

Checklist

• 🛡️ Don't disclose security issues! (contact security@apache.org)
• 🔗 Clearly explained why the changes are needed, or linked related issues: Fixes #
• 🧪 Added/updated tests with good coverage, or manually tested (and explained how)
• 💡 Added comments for complex logic
• 🧾 Updated CHANGELOG.md (if needed)
• 📚 Updated documentation in site/content/in-dev/unreleased (if needed)

[snazy]

Can you verify that this works fine on both macOS and Linux?
Testing against ubuntu:latest is fine.