Add bisect config validation.

scripts/slave/recipes/bisect_test/example_bisect_results.expected/failed_direction_test.json

 [
   {
     "cmd": [
       "git",
       "update-ref",
       "refs/heads/master",
       "refs/remotes/origin/master"
     ],
     "cwd": "[TMP_BASE]/bogus_tmp_1",
     "name": "git update-ref"
   },
   {
     "cmd": [
       "git",
       "checkout",
       "master"
     ],
     "cwd": "[TMP_BASE]/bogus_tmp_1",
     "name": "git checkout"
   },
   {
     "cmd": [],
     "cwd": "[SLAVE_BUILD]",
     "name": "config",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@Bisect job configuration@{@@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"bad_revision\": \"314017\", @@@",
-      "@@@STEP_LOG_LINE@Bisect job configuration@  \"bug_id\": \"\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"builder_host\": \"master4.golo.chromium.org\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"builder_port\": \"8341\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"bypass_stats_check\": \"True\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"command\": \"src/tools/perf/run_benchmark -v --browser=release smoothness.tough_scrolling_cases\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"dummy_builds\": \"True\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"dummy_job_names\": \"True\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"good_revision\": \"314015\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"gs_bucket\": \"chrome-perf\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"max_time_minutes\": \"5\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"metric\": \"mean_input_event_latency/mean_input_event_latency\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"repeat_count\": \"2\", @@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@  \"skip_gclient_ops\": \"True\", @@@",
-      "@@@STEP_LOG_LINE@Bisect job configuration@  \"test_type\": \"perf\", @@@",
-      "@@@STEP_LOG_LINE@Bisect job configuration@  \"truncate_percent\": \"0\"@@@",
+      "@@@STEP_LOG_LINE@Bisect job configuration@  \"test_type\": \"perf\"@@@",
       "@@@STEP_LOG_LINE@Bisect job configuration@}@@@",
       "@@@STEP_LOG_END@Bisect job configuration@@@"
     ]
   },
   {
     "cmd": [],
     "cwd": "[SLAVE_BUILD]",
     "name": "Resolving reference range"
   },
   {
@@ skipping 69 matching lines @@
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::perf_dashboard]/resources/post_json.py"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "Post bisect results",
-    "stdin": "{\"data\": {\"aborted_reason\": \"The metric values for the initial \\\"good\\\" and \\\"bad\\\" revisions match the expected direction of improvement. Thus, likely represent an improvement and not a regression.\", \"bad_revision\": \"deadbeef\", \"bisect_bot\": \"linux_perf_tester\", \"bug_id\": \"\", \"buildbot_log_url\": \"http://build.chromium.org/p/chromium/builders//builds/\", \"change\": null, \"command\": \"src/tools/perf/run_benchmark -v --browser=release smoothness.tough_scrolling_cases\", \"culprit_data\": null, \"good_revision\": \"c001c0de\", \"metric\": \"mean_input_event_latency/mean_input_event_latency\", \"revision_data\": [], \"score\": 0, \"status\": \"completed\", \"test_type\": \"perf\", \"try_job_id\": null, \"warnings\": [\"This is a demo warning\"]}, \"url\": \"https://chromeperf.appspot.com/post_bisect_results\"}",
+    "stdin": "{\"data\": {\"aborted_reason\": \"The metric values for the initial \\\"good\\\" and \\\"bad\\\" revisions match the expected direction of improvement. Thus, likely represent an improvement and not a regression.\", \"bad_revision\": \"deadbeef\", \"bisect_bot\": \"linux_perf_tester\", \"bug_id\": null, \"buildbot_log_url\": \"http://build.chromium.org/p/chromium/builders//builds/\", \"change\": null, \"command\": \"src/tools/perf/run_benchmark -v --browser=release smoothness.tough_scrolling_cases\", \"culprit_data\": null, \"good_revision\": \"c001c0de\", \"metric\": \"mean_input_event_latency/mean_input_event_latency\", \"revision_data\": [], \"score\": 0, \"status\": \"completed\", \"test_type\": \"perf\", \"try_job_id\": null, \"warnings\": [\"This is a demo warning\"]}, \"url\": \"https://chromeperf.appspot.com/post_bisect_results\"}",
     "stdout": "/path/to/tmp/json",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"status_code\": 200@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]