Align openEO and OAP job link relation type `monitor`

[fmigneault]

          > In openEO we use the relation type `monitor` for logs...

This seems like another incompatibility with OGC API - Processes that uses rel=monitor for the job itself: https://docs.ogc.org/is/18-062r2/18-062r2.html#req_core_job-results-success-sync

Originally posted by @fmigneault in #419 (comment)