[core][gcs] Fix task events profile events per task leak (#42248)

[rickyyx]

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Why are these changes needed?

When a long running task keeps submitting tasks (e.g. driver task, actor task), it generates many profile events as part of task submission.

While we already cap the number of profile events in a task at the core worker (where task events are produced and reported), we are not doing that on GCS (the sink), so it's possible when new task events merged to existing ones, it goes unbounded.

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