updated test_param_scheduler replacing multiple calls with pytest.parametrize

[Ishan-Kumar2]

Addresses #2522

Description:
Updated handlers/test_param_scheduler replacing multiple calls with pytest.parametrize

Haven't converted

ignite/tests/ignite/handlers/test_param_scheduler.py

Line 812 in 69ea3c8

def test_simulate_and_plot_values():

and

ignite/tests/ignite/handlers/test_param_scheduler.py

Line 1228 in 69ea3c8

def test_scheduler_with_param_groups():

because it has conditional calls. We could have different fixtures for all the cases but I believe that would make the code less readable, let me know what you think would be best for these tests.
Check list:

• New tests are added (if a new feature is added)
• New doc strings: description and/or example code are in RST format
• Documentation is updated (if required)

[vfdev-5]

@Ishan-Kumar2 thanks for the PR, I left a comment to address.

We could have different fixtures for all the cases but I believe that would make the code less readable, let me know what you think would be best for these tests.

I agree, let's keep them as they are now...

[vfdev-5]

@Ishan-Kumar2 LGTM, thanks for the PR !