[Refactor] Fix the unittest setup scripts for OSDC containers

[huydhn]

First of three. Three container differences that only appear once the job runs inside the image rather than beside it on an EC2 host. All are backward-compatible, so this lands safely before anything moves fleet.

• /usr/share/glvnd/egl_vendor.d is a read-only mount under the NVIDIA container runtime. libglvnd searches <sysconfdir>/glvnd/egl_vendor.d first, so install there and skip when the runtime already supplied the file. Six scripts.
• libgl1-mesa-glx and freeglut3 are gone on noble. libgl1 libglx-mesa0 and freeglut3-dev replace them and resolve on jammy too (verified with apt-get install -s on both).
• Nothing puts the container hostname in its /etc/hosts, so socket.gethostbyname(socket.gethostname()) raises gaierror. torchrl's distributed transport uses it to pick the dist.TCPStore address.

Stacked below #4532 and #4530.

Authored with Claude Code.

[pytorch-bot]

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✅ You can merge normally! (8 Unrelated Failures)

As of commit 034fd2c with merge base 648f50c ():

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• Examples Tests on Linux / tests (3.12, 13.0, 1) / linux-job (gh) (trunk failure)
  AttributeError: module 'ray.internal' has no attribute 'free'
• Examples Tests on Linux / tests (3.12, 13.0, 2) / linux-job (gh) (trunk failure)
  AttributeError: module 'ray.internal' has no attribute 'free'
• Unit-tests on Linux / tests-cpu (3.10, collectors) / linux-job (gh) (trunk failure)
  test/test_collectors.py::TestCollectorStats::test_ray_collector_stats
• Unit-tests on Linux / tests-cpu (3.13, collectors) / linux-job (gh) (trunk failure)
  test/test_collectors.py::TestCollectorStats::test_ray_collector_stats
• Unit-tests on Linux / tests-gpu (3.12, 13.0, 2) / linux-job (gh) (trunk failure)
  test/test_inference_server.py::TestProcessSlotTransport::test_server_batched_pass_on_cuda[True]
• Unit-tests on Linux / tests-gpu-distributed (3.12, 13.0) / linux-job (gh) (trunk failure)
  test/test_distributed.py::TestRayCollector::test_ray_collector_policy_constructor
• Unit-tests on Linux / tests-stable-gpu (3.12, 13.0, 2) / linux-job (gh) (trunk failure)
  test/test_inference_server.py::TestProcessSlotTransport::test_server_batched_pass_on_cuda[True]
• Unit-tests on Linux / tests-stable-gpu-distributed (3.12, 13.0) / linux-job (gh) (trunk failure)
  test/test_distributed.py::TestRayCollector::test_ray_collector_policy_constructor

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[huydhn]

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