fix(preflight): add tracing span and align error handling for host collector redaction

[xavpaice]

Follow-up to #2101.

#2101 added redaction for local host preflight collectors, which was the only collection path that skipped redaction entirely. This PR addresses the review feedback that was not included before #2101 was merged:

1. Adds an OpenTelemetry span around the redaction step, matching the tracing already present for host and in-cluster collectors in the support-bundle path.
2. Aligns the error handling: when redaction fails, "CollectHostWithContext" now returns the unredacted "collectResult" along with the error, matching the behavior of "remote_collector.RunCollectorSync" and "supportbundle.runHostCollectors". This prevents SDK consumers from seeing inconsistent return behavior across collection paths.

The regression test added in #2101 ("TestCollectHostWithContext_RedactsSensitiveEnvValues") continues to verify that "run" host collector environment variables are redacted before being written to the bundle.

[greptile-apps]

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[xavpaice]

Good catch — fixed. collectResult.AllCollectedData is now assigned before the redaction call, so if redaction fails the returned result still contains the unredacted collected data, consistent with the other collection paths.

[greptile-apps]

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