[feature](be) Add printf string formatting - #68772

The website currently documents `PRINTF` for dev, 4.x, and 3.x and
claims support since 3.0.6, while the master implementation is being
introduced in apache/doris#68772. Remove all six English and Chinese
function reference pages and their sidebar, migration-slug, and
last-update entries.

## Validation

- Changed-link gate: passed with no errors; the six page-deletion
notices were reviewed.
- English/Chinese sync gate: passed with no findings.
- Reference and JSON checks: passed; no remaining SQL `PRINTF`
references, document paths, or sidebar entries.
- `git diff --check`: passed.
- Docusaurus content and route loading: passed for dev, 4.x, and 3.x in
both English and Chinese; each locale has 4,582 routes and no `PRINTF`
route. Neighboring function pages and all three sidebars load
successfully.
- Docusaurus English production build: passed for dev, 4.x, and 3.x
(unaffected blog, community, releases, and course plugins excluded).
- Full production build across changed versions and languages: pending
in the PR's Build Check CI.

## Self-review

- Goal: all `PRINTF` SQL function documentation is removed.
- Scope: 13 files, with only the relevant deletions.
- Information architecture: dev, 4.x, and 3.x are updated in both
languages; older versions have no `PRINTF` reference pages.
- Links and navigation: no remaining inbound links or redirect entries
point to the removed pages; removed routes are intentionally retired
without a replacement page.
- Validation: the checks above cover document removal, mirrored
versions/languages, and sidebar integrity.
- Other correctness and usability issues: none found in the changed
content.

## Versions

- [x] dev
- [x] 4.x
- [x] 3.x
- [ ] 2.1 or older (not covered by version/language sync gate)

## Languages

- [x] Chinese
- [x] English

## Docs Checklist

- [x] Checked by AI
- [ ] Test Cases Built (documentation removal; no new SQL examples)
- [x] Updated required version and language counterparts, or explained
why not
- [x] If only one language changed, confirmed whether source/translation
counterparts need sync (both languages updated)