e2e: cozytest prints every HelmRelease snapshot every 2 seconds, so an install log reaches hundreds of MB #4705

While cozy_wait_all_helmreleases_ready polls, cozytest's live trace prints the full HelmRelease snapshot JSON every 2 seconds. A slow install grows the job log to hundreds of megabytes: run 36961209755 (the isp-hosted lane in progress for #3390) produced a 347 MB log for a 31-minute install, and gh run view --log fails on a log that size, so the failing line has to be fetched with an HTTP range request. The same helper runs in the isp-full lanes, so any slow install there inflates the log the same way. Fix shape: print a snapshot only when it changes (or a one-line summary per poll and the full JSON once at timeout), and keep the full dump in the report artifact rather than the step log.