fix(observability): BuildUpdate one-shot guard — flip haveSentBuildUpdate [SDK-6574]

[xxshubhamxx]

What is this about?

The Observability reporter is designed to send BuildUpdate once, but the one-shot guard never flipped its flag. In bin/testObservability/reporter/index.js, the guard is if(!this.haveSentBuildUpdate && ...), but this.haveSentBuildUpdate was never set to true after the event was sent. So it stayed false and BuildUpdate re-fired on every test/hook event — hundreds to thousands of byte-identical observability_version payloads per build (≥10k observed for a single Cypress tenant in prod; 13/13 top BuildUpdate emitters are Cypress across SDK 1.31–1.36.x).

The payload (observability_version) is a build-level constant, so every re-emit is redundant. This floods the TRA event_batch_top_v2 Kafka partition (build-uuid-keyed → hot partition) and drives redundant testhub round-trips.

Fix (additive, one line): set this.haveSentBuildUpdate = true immediately after the BuildUpdate is sent. BuildUpdate now fires once per reporter instance (≈ once per spec process); the byte-identical per-process emits are collapsed to one per build by the consumer-side dedupe in TRAP-4033.

Note: the guard has never worked since it was introduced (commit a0f7404, 2023-06-18) — it is not a recent regression.

Change

         await uploadEventData(buildUpdateData);
+        this.haveSentBuildUpdate = true;
       }

Related Jira task/s

• https://browserstack.atlassian.net/browse/SDK-6574
• Relates: https://browserstack.atlassian.net/browse/TRAP-4033 (consumer-side once-per-build dedupe — the durable backstop for version-pinned customers; complementary to this source fix)

Testing

Single-line change; validated locally (no test file added to keep the PR minimal):

• Reproduce → resolve: a throwaway proxyquire/sinon harness driving 5 test events through one reporter instance emits 5 BuildUpdate without this line and exactly 1 with it.
• No regressions: full npm test suite is unchanged at 678 passing / 13 failing (the 13 are pre-existing failures in unrelated modules — errorReporting / zipUpload / results-table / video-config).