6640 fixes data analyzer device fallback

[wyli]

Fixes #6640

Description

the issue was when device_count==0 fallback to CPU didn't work

[2023-06-26T12:57:56.270Z] 2023-06-26 12:57:56,044 - INFO - test_fl compute data statistics on train...
[2023-06-26T12:57:56.270Z] 2023-06-26 12:57:56,044 - INFO - Found 0 GPUs for data analyzing!
[2023-06-26T12:57:56.270Z] Finished test: test_shape_5 (tests.test_varautoencoder.TestVarAutoEncoder) (0.007s)
[2023-06-26T12:57:56.270Z] Starting test: test_get_data_stats_0 (tests.test_fl_monai_algo_stats.TestFLMonaiAlgo)...
[2023-06-26T12:57:56.526Z] 
  0%|          | 0/2 [00:00<?, ?it/s]2023-06-26 12:57:56,326 - INFO - Unable to process data /home/jenkins/agent/workspace/Monai-pytorch-versions/tests/testing_data/anatomical.nii on cuda:0. No CUDA GPUs are available
[2023-06-26T12:57:56.526Z] 2023-06-26 12:57:56,326 - INFO - DataAnalyzer `device` set to GPU execution hit an exception. Falling back to `cpu`.
[2023-06-26T13:19:27.823Z] 
 50%|█████     | 1/2 [00:00<00:00,  3.17it/s]Sending interrupt signal to process
[2023-06-26T13:19:27.824Z] Killing processes

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.

[KumoLiu]

LGTM

[wyli]

/integration-test
/build