Lately we have observed that some builds are missing the package_url in the build metadata. This is usually caused by changes in how build metadata is stored on the servers and the s3 reloc server failing to dig them out of the metadata files. A user can usually still obtain the package url but currently there is no way to plug in user-obtained scylla package into the script's workflow.
This PR fixes this by allowing the user to provide the package as `$ARTIFACT_DIR/scylla.package` (in unpacked form).
Closes#13519
* github.com:scylladb/scylladb:
scripts/open-coredump.sh: allow bypassing the package downloading
scripts/open-coredump.sh: check presence of mandatory field in build json object
scripts/open-coredump.sh: more consistent error messaging
4e7f4b9303