Refactor SyncBuildAndRunRevision to remove deep nesting.

I also propose to rename this function to just RunTest, because its purpose is to do everything necessary to obtain a build and run a test to get results, and it's a relatively important and high-level function.

"Flat is better than nested."
  -- The Zen of Python, PEP 20.

BUG=

Review URL: https://codereview.chromium.org/484583002

Cr-Commit-Position: refs/heads/master@{#292661}

tools/auto_bisect/bisect.cfg

@@ -59,13 +59,17 @@ config = {
 """
 
 config = {
-  'command': '',
-  'good_revision': '',
-  'bad_revision': '',
-  'metric': '',
-  'repeat_count':'',
-  'max_time_minutes': '',
-  'truncate_percent':'',
+  'max_time_minutes': '20',
+  'metric': 'Total/Total',
+  'builder_port': '8341',
+  'bug_id': '405188',
+  'repeat_count': '20',
+  'good_revision': '288423',
+  'builder_host': 'master4.golo.chromium.org',
+  'truncate_percent': '25',
+  'command': 'tools/perf/run_benchmark -v --browser=release sunspider',
+  'gs_bucket': 'chrome-perf',
+  'bad_revision': '288447',
 }
 
 # Workaround git try issue, see crbug.com/257689