test(ci): per-test start diag + drop stray console.log noise

Follow-up to the heartbeat PR after run 26397693748 confirmed the
diagnostic works (the kill landed at importexportGetPost.ts
'Import authorization checks > authn anonymous !exist -> fail',
~300 ms after the previous test's ✔). Two cleanups so the next
failure pinpoints faster and reads cleaner:

1. diagnostics.ts: emit a `test start: <name>` diag line in the
   mocha beforeEach hook, after setting the currentTest pointer.
   The 1Hz heartbeat misses tests that take less than a second,
   and the silent kills land ~300 ms after a test boundary —
   precisely the gap where heartbeat resolution fails. A start
   line per test gives sub-millisecond resolution on which test
   was on the rails when the process died.

2. specs/api/importexportGetPost.ts: drop a stray
   `console.log(importedPads)` debug leftover (and the duplicate
   `await importEtherpad(records)` only present to feed it) in
   the `malformed .etherpad files are rejected` block. The leftover
   dumped a ~600-line reflection of a supertest Response object
   to the CI log on every successful run, drowning the surrounding
   test output and making the silent-kill window much harder to
   read.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: JohnMcLear

src/tests/backend/diagnostics.ts

@@ -131,10 +131,17 @@ for (const sig of ['SIGINT', 'SIGTERM', 'SIGHUP', 'SIGBREAK'] as const) {
 // Mocha root hooks — only registered if mocha picks up this file via --require.
 // beforeEach sets the running pointer so a mid-test kill is attributable to a
 // specific test, not just the previous one that successfully finished.
+//
+// We also emit a synchronous diag line on every test start. The 1Hz heartbeat
+// misses tests that take less than a second, and the silent backend-test
+// kills land ~300 ms after a test boundary — exactly the gap where heartbeat
+// resolution fails us. A `start` line per test gives sub-millisecond
+// resolution on which test was on the rails when the process died.
 export const mochaHooks = {
   beforeEach(this: any) {
     if (this.currentTest) {
       currentTest = this.currentTest.fullTitle();
+      diag(`test start: ${currentTest}`);
     }
   },
   afterEach(this: any) {

src/tests/backend/specs/api/importexportGetPost.ts

@@ -418,8 +418,6 @@ describe(__filename, function () {
         // that a buggy makeGoodExport() doesn't cause checks to accidentally pass.
         const records = makeGoodExport();
         await deleteTestPad();
-        const importedPads = await importEtherpad(records)
-        console.log(importedPads)
         await importEtherpad(records)
             .expect(200)
             .expect('Content-Type', /json/)