cbuildbot_config_unittest.py: test correctness of config_dump.json
cbuildbot_config_unittest.py: test correctness of config_dump.json

BUG=chromium:369175
TEST=Unit test passes. Unit test fails if config_dump.json is manually
modified to be incorrect.

Change-Id: I922f88246b734e79e0202b79e30aba240875874b
Reviewed-on: https://chromium-review.googlesource.com/197850
Reviewed-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Commit-Queue: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite