Reduce integation test suite time

[BradyPlanden]

Feature description

Currently the integration suite takes approximately ~20 minutes to complete on the Github runners. This can be reduced by shrinking the number of solution points in the synthetic prediction data. This issue is to reduce the integration testing suite time while still maintaining the performance assertions.

Motivation

No response

Possible implementation

Increase the sample period in the model prediction:

PyBOP/tests/integration/test_parameterisations.py

Line 251 in 57e0e83

"Discharge at 0.5C for 3 minutes (1 second period)",

Additional context

No response