[WIP] Migration to Java 25

[ViacheslavKlimov]

Summary

Migrate all ThingsBoard and Edge documentation from Java 17 to Java 25 (LTS) for the upcoming v4.4 release. This includes installation guides, upgrade instructions, and related references. Also adds TBEL date formatting change warnings for all upgrade paths.

Scope: ThingsBoard CE/PE + Edge CE/PE only. Trendz, TBMQ, Cassandra-related instructions, historical release notes, and blog posts are intentionally unchanged.

Changes

OS Version Updates

• Removed Ubuntu 20.04 (EOL) from HAProxy prerequisites
• Updated AWS and GCP self-hosted setup guides: Ubuntu 20.04 → 24.04
• Updated DigitalOcean droplet guide: Ubuntu 18.04 → 24.04
• Updated installation option descriptions for CE, PE, Edge CE, and Edge PE: removed Ubuntu 18.04/20.04, now lists Ubuntu 22.04 / 24.04

Core Java Install Templates (highest impact — used by dozens of pages)

• ubuntu-java-install.md — openjdk-17-jdk-headless → openjdk-25-jdk-headless
• rhel-java-install.md — java-17-openjdk-headless → java-25-openjdk-headless, added RHEL 8 compatibility warning
• windows-java-install.md — Adoptium version 17 - LTS → 25 - LTS, updated Temurin version output

Installation Guide Headings (~15 files)

• All Step 1. Install Java 17 (OpenJDK) → Step 1. Install Java 25 (OpenJDK) across CE, PE, Edge CE, and Edge PE install guides

Windows install.bat Output Examples

• Updated CurrentVersion 170 → 250 and Java 17 found! → Java 25 found! in CE and PE Windows guides

Edge-Specific Files

• Updated Java version headings in Edge integration resource templates (Ubuntu, CentOS/RHEL)
• Updated proxy guide prerequisite: Java 17 → Java 25
• Updated Edge Windows install output: Java 11 found! → Java 25 found!

Historical v3.7 Upgrade Notes (made self-contained)

• tb-370-update-linux.md — replaced anchor links to install pages with inline apt/dnf commands
• tb-370-update-windows.md — replaced anchor link with inline Adoptium download instruction
• This prevents broken links now that install pages reference Java 25 instead of 17

TBEL Date Formatting Changes Documentation

• Added Date formatting changes in ThingsBoard 4.4+ section to tbel.md with:
  • Table of before/after locale formatting differences (English, Ukrainian, Arabic)
  • Lists of affected vs unaffected TbDate methods
  • Recommendations (use toISOString(), explicit patterns, numeric getters)
• TBEL warning shown in upgrade instructions for all environments (Ubuntu, CentOS, Windows, Docker, Docker Compose)

Other Documentation References

• building-from-source.md (CE + Edge) — Java 17 → 25, updated anchor links
• tbel.md — "currently uses Java 17" → "Java 25"
• mcp-server.md — "Java 17 or later" → "Java 25 or later"
• rule-node-development.md — "OpenJDK 17" → "OpenJDK 25", updated anchor
• remote-integrations.md — "Install Java 17" → "Install Java 25" (Ubuntu + RHEL sections)

Files NOT Modified (intentional)

• Release notes and blog posts (historical records)
• Trendz and TBMQ documentation (out of scope)
• Cassandra install templates (per scope)
• IoT Gateway installation options (out of scope)
• docs/user-guide/install/linux.md (redirect page — content never shown)