Update MaxScale SBOM Format to .cdx.json for Vulnerability Scanning Compatibility

The current file format for the SBOM files for MaxScale are provided only in .tgz format which are not compatible for automated security tooling.
Issue:

• The Security team’s vulnerability scanning tools are configured to locate SBOMs using the pattern:

  {product}/**/{version}/**/*.cdx.json

• .tgz-formatted SBOMs are not recognized or scanned, which creates a gap in automated security coverage.

MaxScale SBOMs should be made available in the .cdx.json format, similar to how it is published for MariaDB Enterprise Server.

• https://dlm.mariadb.com/browse/mariadb_enterprise_server/11.4.5-3/SBOM/