DOC: Save File Image not found when generating Docs in parallel
#### Problem description

As a part of #27804 I tried adding `num-jobs=4` while generating docs. But the doc generation part fails since `doc/source/whatsnew/v0.7.3.rst` file refers to an image in `../savefig/scatter_matrix_kde.png` which is not generated from `doc/source/user_guide/visualization.rst`

#### Proposed solutions

Few solutions from the top of my mind
1. We can move these referenced files and have a static copy in `_static`(there are only 4 files we need to copy)
2. Remove these references from the `v0.7.3` since it is outdated

Discussing this with @datapythonista open to the community's thought on this.