Attempt to remove AWS S3 flaky cache for sccache (#2953)
* backend(trtllm): attempt to remove AWS S3 flaky cache for sccache
* backend(trtllm): what if we expose ENV instead of inline?
* backend(trtllm): and with the right env var for gha sccache
* backend(trtllm): relax the way to detect sccache
* backend(trtllm): make sccache definition manually
* backend(trtllm): ok let's try to define the launchers in build.rs when rustc_wrapper is present
* backend(trtllm): export env variable in run mb?
* backend(trtllm): Cache mode max to cache intermediate layers
* backend(trtllm): inject ompi_version build arg in dependent step