Revert "Reland #2 of "Parallelize fetching telemetry benchmark deps""

This reverts commit c8df13e9.

Reason for revert: Failing on a few builders now in the gclient runhooks step, see crbug.com/1113988

Original change's description:
> Reland #2 of "Parallelize fetching telemetry benchmark deps"
> 
> This reverts commit e6ad8b42.
> 
> Difference from previous reland: using close and join instead of terminate
> 
> Original change's description:
> > Revert "Reland "Parallelize fetching telemetry benchmark deps""
> >
> > This reverts commit 95e22d39.
> >
> > Reason for revert: Potentially breaking many builders, https://crbug.com/1108314
> >
> > Original change's description:
> > > Reland "Parallelize fetching telemetry benchmark deps"
> > >
> > > This is a reland of 8ab0b856
> > >
> > > Original change's description:
> > > > Parallelize fetching telemetry benchmark deps
> > > >
> > > > The fetching script currently fetches about 2 GB (on my linux workstation)
> > > > from cloud storage serially. This can (and is) trivially parallelizable, and
> > > > should speed up the fetching script significantly.
> > > >
> > > > This script has been taking 20 minutes on mac machines for a long time. This
> > > > will hopefully significantly speed the mac builders up.
> > > >
> > > > Bug: 1102597
> > > > Change-Id: I93d2fa2b1f4b4ef6e27e9c894a9dd4c0d0e12d7b
> > > > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2285503
> > > > Commit-Queue: Stephen Martinis <martiniss@chromium.org>
> > > > Reviewed-by: Wenbin Zhang <wenbinzhang@google.com>
> > > > Reviewed-by: John Chen <johnchen@chromium.org>
> > > > Cr-Commit-Position: refs/heads/master@{#786521}
> > >
> > > Bug: 1102597
> > > Change-Id: I37d0055fadb26bf4eae2b0b5fe0ecc4732edde3d
> > > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2288740
> > > Commit-Queue: Stephen Martinis <martiniss@chromium.org>
> > > Reviewed-by: John Chen <johnchen@chromium.org>
> > > Cr-Commit-Position: refs/heads/master@{#789736}
> >
> > TBR=martiniss@chromium.org,johnchen@chromium.org,wenbinzhang@google.com
> >
> > # Not skipping CQ checks because original CL landed > 1 day ago.
> >
> > # Tree is currently closed, trying to fix an outage
> >
> > No-Try: true
> > No-Tree-Checks: true
> > Bug: 1102597
> > Change-Id: If6b95395208a3136a798118e4eb229e4322c7878
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2317774
> > Commit-Queue: Stephen Martinis <martiniss@chromium.org>
> > Reviewed-by: Stephen Martinis <martiniss@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#791304}
> 
> TBR=martiniss@chromium.org,johnchen@chromium.org,wenbinzhang@google.com
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 1102597
> Change-Id: I2f9a7162e73ee264ed9f0f844f45106160bce793
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2339589
> Commit-Queue: Stephen Martinis <martiniss@chromium.org>
> Reviewed-by: Stephen Martinis <martiniss@chromium.org>
> Reviewed-by: Wenbin Zhang <wenbinzhang@google.com>
> Cr-Commit-Position: refs/heads/master@{#795751}

TBR=martiniss@chromium.org,johnchen@chromium.org,wenbinzhang@google.com

Change-Id: Ia31da9d6b6fd00f6e0105314955d8f0bfe830b05
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1102597
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342228Reviewed-by: Patti <patricialor@chromium.org>
Commit-Queue: Patti <patricialor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795761}

tools/perf/fetch_benchmark_deps.py

@@ -7,11 +7,10 @@
 
 import argparse
 import json
-import logging
-import multiprocessing
 import optparse
 import os
 import sys
+import logging
 
 from chrome_telemetry_build import chromium_config
 from core import benchmark_finders
@@ -122,13 +121,8 @@ def main(args):
       raw_input(
           'No benchmark name is specified. Fetching all benchmark deps. '
           'Press enter to continue...')
-    benchmarks = benchmark_finders.GetOfficialBenchmarks()
-    p = multiprocessing.Pool()
-    results = p.map(_FetchDepsForBenchmark, benchmarks)
-    p.close()
-    p.join()
-    for benchmark, result in zip(benchmarks, results):
-      deps[benchmark.Name()] = result
+    for b in benchmark_finders.GetOfficialBenchmarks():
+      deps[b.Name()] = _FetchDepsForBenchmark(b)
 
   if options.output_deps:
     with open(options.output_deps, 'w') as outfile: