Cleanup: Fix typos in tests subdirectory

Fixes various typos

Co-authored-by: luz paz
Pull Request: https://projects.blender.org/blender/blender/pulls/148090

tests/coverage/coverage_report/index_template.html

@@ -388,7 +388,7 @@
       }
 
       // Makes sure that the html elements for a specific row (and all its parents) have been created.
-      // This data is gnerated lazily to improve start-up time.
+      // This data is generated lazily to improve start-up time.
       function ensure_dom_for_row(row) {
         if (row.dom_elem) {
           return;