Revert "[Jobs]: Boost WaitForConcurrencyIncreaseUpdate timeout to 30sec."

This reverts commit 665132b2.

Reason for revert: Causes Jobs tests (e.g. StaleConcurrency) to flakily timeout.

Original change's description:
> [Jobs]: Boost WaitForConcurrencyIncreaseUpdate timeout to 30sec.
> 
> To avoid flaky failures with slow running tests.
> 
> Bug: 1046343
> Change-Id: Iafb6d15c08fb8c97eaa36d802cee5f993eceacd8
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2107602
> Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
> Reviewed-by: Gabriel Charette <gab@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#751380}

TBR=gab@chromium.org,etiennep@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1046343, 1064953
Change-Id: I6d9e3bbede1c85098ec2bdbca3f25b48a2909e94
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2124527Reviewed-by: Etienne Pierre-Doray <etiennep@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#754486}

base/task/thread_pool/job_task_source.cc

@@ -336,11 +336,7 @@ size_t JobTaskSource::GetConcurrencyIncreaseVersion() const {
 
 bool JobTaskSource::WaitForConcurrencyIncreaseUpdate(size_t recorded_version) {
   AutoLock auto_lock(version_lock_);
-  // This timeout is meant to catch a JobDelegate which forgets to decrease the 
-  // max-concurrency it returns despite workers returning (hence entering an 
-  // infinite loop of workers being spawned with no work to do). 30 seconds 
-  // catches this error early enough without causing false positives.
-  constexpr TimeDelta timeout = TimeDelta::FromSeconds(30);
+  constexpr TimeDelta timeout = TimeDelta::FromSeconds(1);
   const base::TimeTicks start_time = subtle::TimeTicksNowIgnoringOverride();
   do {
     DCHECK_LE(recorded_version, increase_version_);