## Why
Failed snapshot assertions should print their diffs without leaving `.snap.new` files after a passing retry. The OTLP loopback collector should stop once exporter shutdown completes instead of waiting for its deadline.
## What changed
- Set `INSTA_UPDATE=no` for Bazel CI tests, including the local configuration used when no BuildBuddy API key is available.
- Initialize the OTLP provider before starting the collector's deadline in the Tokio bounded-shutdown test.
- Signal the collector to stop after shutdown and join its thread before propagating any shutdown error.
GitOrigin-RevId: 55b050822ec923894c9edbc8f039f35f693a4b7e