Add cleanup for .bst and .cls files in extension tests

The acs and elsevier journal extensions copy .bst and .cls files to
the test directory during rendering. These files were not being
cleaned up by teardown, leaving artifacts after test runs.

(cherry picked from commit b8421ca)

Author: cderv

tests/smoke/render/render-format-extension.test.ts

@@ -86,8 +86,9 @@ testRender(
     setup: updateExtensions,
     // deno-lint-ignore require-await
     teardown: async () => {
-      // Clean up the bib file that is generated by the elesevier class
+      // Clean up files generated by the acs extension
       safeRemoveSync(docs("extensions/format/academic/acs-document.bib"));
+      safeRemoveSync(docs("extensions/format/academic/achemso.bst"));
     },
   },
 );
@@ -100,8 +101,10 @@ testRender(
     setup: updateExtensions,
     // deno-lint-ignore require-await
     teardown: async () => {
-      // Clean up the SPL file that is generated by the elesevier class
+      // Clean up files generated by the elsevier extension
       safeRemoveSync(docs("extensions/format/academic/document.spl"));
+      safeRemoveSync(docs("extensions/format/academic/elsarticle.cls"));
+      safeRemoveSync(docs("extensions/format/academic/elsarticle-num.bst"));
     },
   },
 );
@@ -116,8 +119,10 @@ testRender(
     setup: updateExtensions,
     // deno-lint-ignore require-await
     teardown: async () => {
-      // Clean up the SPL file that is generated by the elesevier class
+      // Clean up files generated by the elsevier extension
       safeRemoveSync(docs("extensions/format/academic/document+foobar.spl"));
+      safeRemoveSync(docs("extensions/format/academic/elsarticle.cls"));
+      safeRemoveSync(docs("extensions/format/academic/elsarticle-num.bst"));
     },
   },
 );