Issue with PDHG result not matching FISTA in 01_optimisation

[lauramurgatroyd]

The notebook claims that the result of PDHG will look the same as the result of FISTA

However, this is what I get with PDHG:

This was the FISTA result:

Also with PDHG I get a warning:
miniconda3/envs/cil_24.2/Lib/site-packages/cil/optimisation/algorithms/PDHG.py:393: UserWarning: Convergence criterion of PDHG for scalar step-sizes is not satisfied.
warnings.warn("Convergence criterion of PDHG for scalar step-sizes is not satisfied.")

[MargaretDuff]

To get rid of the error - add "check_convergence = False" to the PDHG set up. I will add an issue in CIL to remove this but this will be a future version and we want to run the notebooks on 24.2.0

[MargaretDuff]

The notebook first runs 500 iterations of PDHG

and then further runs up to 5000 iterations of PDHG for the primal dual gap to shrink:

I suggest we change the statement that the FISTA and PDHG results will look the same to be in reference to the 5000 iteration image

[lauramurgatroyd]

Currently can't add convergence check due to TomographicImaging/CIL#1965