fix(regression): Make test_analyze_mv row_count assertion stable after truncate

[yujun777]

Problem

statistics/test_analyze_mv.groovy line 614 asserts assertEquals("-1", result_row[0][4]) immediately after truncate table, expecting report_row_count_for_nereids to be -1 (unreported). This is a race condition: BE asynchronously reports new tablet stats (0 rows for empty table) to FE, and if the report arrives before the assertion, the value is 0 instead of -1.

On cloud, this is amplified by CloudTabletStatMgr unconditionally setting rowCountReported=true, making the -1 state exceptionally short-lived or unobservable.

Root Cause

After truncate table, the FE stat manager (CloudTabletStatMgr / TabletStatMgr) updates MaterializedIndex.rowCount and sets rowCountReported=true. The test assertion races with this update:

• If BE hasn't reported yet → getRowCountForIndex(id, true) returns -1 ✓
• If BE has reported → returns 0 ✗ (test fails)

Fix

Change the assertion to accept both -1 and 0, since both are valid states for an empty table after truncate:

• -1: tablet row count not yet reported
• 0: tablet row count reported as 0 (empty table)

Add assertion message with actual value for debuggability.

🤖 Generated with Claude Code

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