[sglang] Upgrade sglang to 0.4.6.post1 & misc fixes

[ocss884]

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What does this PR do?

• upgrade required sglang version to 0.4.6.post1 which suports Qwen3
• fix: flush_cache was never awaited
• remove unused env
• fix: add rank num to port to avoid SGLang picking the same port when random.seed being set
• feat: disable SGLang memory inbalance check by default Fix: fix the exception 'the memory capacity is unbalanced. Some GPUs … sgl-project/sglang#5426
• update setup.py to avoid old version pip can not resolving deps
• fix: tools_kwargs length mismatch with batch Running GRPO example on latest commit yields tools_kwargs length mismatch #1380

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• Training: [Note which backend this PR will affect: FSDP, Megatron, both, or none]
• Inference: [Note which backend this PR will affect: vLLM, SGLang, both, or none]

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[zhaochenyang20]

thanks! In SGLang, we now do not have a four GPU test to secure the usage of tp 2 dp 2.

There are two PRs on this:

sgl-project/sglang#6007

sgl-project/sglang#5997

We will merge the second one ASAP in SGLang. And verify the usage of Qwen3 today.

[eric-haibin-lin]

Waiting for the CI to completion. Is it better to add a qwen3 rollout unit test that reproduces the issue?

[zhaochenyang20]

Waiting for the CI to completion. Is it better to add a qwen3 rollout unit test that reproduces the issue?

not from Qwen3. No need to worry.

[zhaochenyang20]

We shall add CI in SGLang.

sgl-project/sglang#6007