v3.14.3 — sync tests/ to v3.14.2 provider audit

Pure tests/ patch. No prod code, no API, no docs/, no compose, no
litellm config.

The v3.14.2 release removed sunset-flagged Groq / Cerebras /
OpenRouter aliases and added new free-tier candidates, but the
shell test suite (tests/test_*.sh) still referenced the dead
aliases. This patch syncs them.

tests/test_litellm.sh — EXPECTED_MODELS array:
  - removed: groq-llama-3.1-8b, groq-llama-3.3-70b,
             groq-llama-4-scout, groq-kimi-k2, groq-qwen3-32b,
             cerebras-qwen3-235b, cerebras-llama-3.1-8b,
             or-minimax-m2.5.
  - added:   groq-qwen3.6-27b, groq-gpt-oss-safeguard-20b,
             or-nemotron-ultra-550b, or-nemotron-nano-9b,
             or-nemotron-nano-30b.

Inline POST swaps in test_integration.sh, test_piston.sh,
test_proxq.sh, test_security.sh, test_telethon.sh — all
deprecated model names → their recommended replacements.

shellcheck clean on all six. Patch bump.