Update figure-generating notebook

[tsalo]

Closes none. I figure that we've made a bunch of changes to the codebase that should be reflected in the documentation (e.g., the adaptive mask).

Changes proposed in this pull request:

• Update the walkthrough notebook to follow the current output filename convention.
• Update the denoising approach page's figures.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.91%. Comparing base (0f6cbe1) to head (5f6354b).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1074 +/- ## ======================================= Coverage 89.91% 89.91% ======================================= Files 26 26 Lines 3621 3621 Branches 629 629 ======================================= Hits 3256 3256 Misses 214 214 Partials 151 151 ```

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