[wip]: chore/debug gpu tests

[bhimrazy]

What does this PR do?

• fix: unzip not found

.actions/pull_legacy_checkpoints.sh: line 10: unzip: command not found
total 0
+ cd tests/legacy
+ ls -lh checkpoints/
total 0

• two of these tests seems to take more than 20 minutes but when run manually finished with in 5s [ debugging ]

============================= slowest 50 durations =============================
790.52s call     tests/tests_pytorch/models/test_torch_tensorrt.py::test_tensorrt_save_ir_type[ts-ScriptModule]
778.97s call     tests/tests_pytorch/models/test_torch_tensorrt.py::test_tensorrt_export_reload[ts-torchscript]

#manually

tests/tests_pytorch/models/test_torch_tensorrt.py::test_tensorrt_save_ir_type[default-GraphModule] PASSED
tests/tests_pytorch/models/test_torch_tensorrt.py::test_tensorrt_save_ir_type[dynamo-GraphModule] PASSED
tests/tests_pytorch/models/test_torch_tensorrt.py::test_tensorrt_save_ir_type[ts-ScriptModule] WARNING: [Torch-TensorRT] - For input x.1, found user specified input dtype as Float. The compiler is going to use the user setting Float
PASSED

================================================= 3 passed, 12 deselected, 2 warnings in 4.93s =================================================

Fixes #<issue_number>

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[bhimrazy]

It seems the delay in those tests is caused by CUDA_LAUNCH_BLOCKING=1.

Test Code

export CUDA_LAUNCH_BLOCKING=0
time python -c "
import torch
from lightning.pytorch.demos.boring_classes import BoringModel
model = BoringModel()
model.example_input_array = torch.randn((4, 32))
model.cuda()
print('Starting compilation with CI env vars...')
import time
start = time.time()
ret = model.to_tensorrt(ir='ts')
end = time.time()
print(f'Compilation took {end - start:.2f} seconds')
"

Almost 20 mins saved