Live singles fits plot names

[GarethCabournDavies]

Fix an annoyance in the naming of single significance plots for each IFO.

Also remove unused options

Standard information about the request

This is a minor fix
This change affects the live search
This change changes naming of live automatically produced plots

This change follows style guidelines (See e.g. PEP8), has been proposed using the contribution guidelines

Contents

Change to use a daily singles fit filename format which uses IFOs, and then replaces that string for the single-ifo plots

Testing performed

Supervisor script still runs and makes plots with the appropriate name (once the config is updated as appropriate)

• The author of this pull request confirms they will adhere to the code of conduct

[maxtrevor]

Changes all make sense, approving. That said, merging is currently blocked by CI issues

[titodalcanton]

Please rebase on master to pick up #4855 and get the tests to pass.