[CI] Inline env vars lost by CONTINUE_ON_FAILURE subshell wrapping
Postmerge/nightly/daily builds set CONTINUE_ON_FAILURE=1, which wraps
each YAML command in `(cmd) || CI_OVERALL_STATUS=1`. A standalone
`export VAR=val` executes inside the subshell and the variable is
immediately lost — subsequent commands never see it.
This caused real failures (model_executor fastsafetensors crash from
missing VLLM_WORKER_MULTIPROC_METHOD=spawn) and silent coverage gaps
(rust_frontend tests silently running the Python frontend because
VLLM_USE_RUST_FRONTEND=1 was never set).
Fix: inline env vars as command prefixes (`VAR=val command`) instead
of standalone `export` lines across all 11 affected CI YAML files.
Co-authored-by: Claude <noreply@anthropic.com>
Signed-off-by: Tyler Michael Smith <tyler@tylermsmith.com>
Signed-off-by: Tyler Michael Smith <tlrmchlsmth@gmail.com>
