Switch from stub run tests to use small DBs

[JoseEspinosa]

Description of feature

Currently, tests are run using stub runs as the size of the real DBs are too big. Explore the feasibility of using the mini DBs to run them (though the size of the images could still be an issue).

[tlitfin]

• We can also enable options which reduce execution time requirements
  • eg for AlphaFold2: ext.args = '--num_multimer_predictions_per_model=1'.
• This can limit to a single pass of a model rather than generating many replicates.
• Related PR: Force single pdb workflow outputs to return as a list #409