Fix excldue typo in apache-rat exclude patterns

[tanvir-ux]

What

Fixed <excldue> → <exclude> in the apache-rat plugin config in pom.xml and shenyu-e2e/pom.xml.

Maven silently ignores unknown tags, so **/*.MD was never excluded from license checks.

Why

Part of #6603 — this PR only fixes the typo; I left the CI verify/rat:check change out so this stays a small, safe diff.

Test

Diff-only change to POM exclude tags; no runtime behavior change.

[Aias00]

Summary

Trivial but correct fix: <excldue> → <exclude> in the Apache RAT license-check plugin configuration, in both the root pom.xml and shenyu-e2e/pom.xml.

What is correct

• Maven silently ignores unknown configuration tags, so the original <excldue>**/*.MD</excldue> was a no-op — **/*.MD files were never excluded from RAT license checks. Restoring <exclude> makes the intended exclusion effective again.
• Change is purely declarative (POM exclude tags); no runtime/compiled-behavior change, no functional risk.
• Scope is intentionally small (the author explicitly left the CI rat:check enablement out), which keeps this a safe, low-risk diff.

Verdict

Approve. No blocking issues.

Non-blocking suggestions

• Consider following up in #6603 with the actual rat:check CI enablement so the typo can't silently regress again.