Fix Memory Leaks

[leuty]

When running mover-plot I usually got a lot of the following warnings in plot.log:

RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`). Consider using `matplotlib.pyplot.close()`.

This PR aims at fixing the leaks related to these warnings by closing all the figures that are opened.

Testing:
(a) Warnings are gone for my usecase
(b) I checked with plt.get_fignums() at the end of station_scores.py, time_scores.py, daytime_scores.py and total_scores.py if any figures are left open.
(c) figures are bit identical
(d) wrote unit test that ensure that all figures are closed now

Review:
The PR is best reviewed file by file

[pirmink]

E2e-test with operational verification results for spring 2026 was successful.