Java install docs pin 0.18.0 across six pages #513

All Java install/dependency snippets pin 0.18.0; the current release is 0.21.0. Still present after #510 rewrote installation.mdx — the stale literal propagated into the new classifier-dependency snippets.

Pages:

• docs/content/docs/java/getting-started/installation.mdx
• docs/content/docs/java/guides/resources/testing.mdx
• docs/content/docs/java/api-reference/testing.mdx
• docs/content/docs/java/guides/integrations/index.mdx
• docs/content/docs/java/guides/integrations/spring.mdx
• docs/content/docs/shared/guides/operations/testing.mdx

Found in the 2026-07-24 SDK parity audit (SDK_PARITY_REPORT.md).