ref(data_export): Rename array telemetry attrs to unprefixed names

[manessaraj]

Emit the two array-valued export telemetry attributes as csv_headers and blob_offsets instead of data_export.csv_headers and data_export.blob_offsets, at both the span-data and structured-log sites. The data_export.data_export_id attribute and the dataexport.* log message names are left unchanged.
In current naming structure, the ingestion string-ify the arrays.

[sentry]

Bug: Tests in test_organization_trace_item_attributes.py assert old span attribute names (data_export.csv_headers, data_export.blob_offsets) while the production code now uses new, unprefixed names, causing test failures.
_{Severity: MEDIUM}

Suggested Fix

Update the assertions in test_organization_trace_item_attributes.py to expect the new, unprefixed attribute names csv_headers and blob_offsets instead of the old data_export.csv_headers and data_export.blob_offsets.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: src/sentry/data_export/tasks.py#L186-L187

Potential issue: The production code was updated to set span attributes as `csv_headers`
and `blob_offsets` in `export_chunk_to_stored_blobs()` and `merge_export_blobs()`
respectively. However, the corresponding tests in
`test_organization_trace_item_attributes.py` were not updated. These tests still assert
that the attribute names are the old, prefixed versions: `data_export.csv_headers` and
`data_export.blob_offsets`. This mismatch will cause the test suite to fail, preventing
the changes from being validated correctly.

Also affects:

• src/sentry/data_export/tasks.py:795~796

_{Did we get this right? 👍 / 👎 to inform future reviews.}