[fix](sql-functions) provide setup data for CUME_DIST / DENSE_RANK window examples

[boluor]

The CUME_DIST and DENSE_RANK example pages query tables that the page never defines, so a reader who runs the examples hits table does not exist. This adds the missing setup so both pages are runnable end-to-end.

• cume-dist (dev + 4.x + 3.x + 2.1, EN+ZH): a render-invisible <!-- setup-sql --> block creating the sales table the example prints, loaded with exactly the 8 rows already shown in the doc. CUME_DIST is deterministic (tied values share a cumulative value), and the query has no outer ORDER BY, so the result is compared as a multiset.
• dense-rank (dev + 3.x + 2.1, EN+ZH): port the visible int_t setup block + clean output table that version-4.x already carries, so the older copies match 4.x and become self-contained. (4.x is unchanged.)

No rendered page, expected output, or ja-source/ is altered — pure setup addition (cume-dist) / alignment to the existing 4.x form (dense-rank).

Verification — every touched example was executed end-to-end on fresh single-BE clusters and reproduces the doc's printed output cell-for-cell:

version	cluster	cume-dist	dense-rank
dev	master daily (doris-0.0.0-2e72603618c)	P3 F0 (EN+ZH)	P3 F0 (EN+ZH)
4.x	4.1.1	P3 F0 (EN+ZH)	unchanged (control: P3 F0)
3.x	3.1.4-rc02	P3 F0 (EN+ZH)	P3 F0 (EN+ZH)
2.1	2.1.11-rc01	P3 F0 (EN+ZH)	P3 F0 (EN+ZH)

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