google_scc: use dynamic timestamps in finding pubsub mock data - #20815

google_scc: use dynamic timestamps in finding pubsub mock data

The pubsub system test variant feeds finding.log through `stream log`,
which streamed each line verbatim, so the static eventTime values
(2026-05-20) eventually aged past the latest_cdr_misconfigurations
transform's now-90d window and the transform preview found no documents.

stream v0.25.0 adds a `--template` flag to the log command. Enable it on
the gcppubsub-finding service and replace the static eventTimes with the
same `now -720h` template the httpjson config.yml already uses, so the
findings stay current relative to wall-clock time.

Fixes #20792
Fixes #20791

--- Test results for package: google_scc - START ---
╭────────────┬─────────────┬───────────┬───────────┬────────┬───────────────╮
│ PACKAGE    │ DATA STREAM │ TEST TYPE │ TEST NAME │ RESULT │  TIME ELAPSED │
├────────────┼─────────────┼───────────┼───────────┼────────┼───────────────┤
│ google_scc │ finding     │ system    │ pubsub    │ PASS   │ 38.900429875s │
╰────────────┴─────────────┴───────────┴───────────┴────────┴───────────────╯
--- Test results for package: google_scc - END   ---
Done