Change disable_bazel_mode_by_default feature to deprecate_bazel_mode

* Rename the feature to be more precise.
* Only evaluate the enablement where it's needed. Previously it's evaluated for all tests.
* Now user can't use --bazel-mode to override, and they will see the message print if they do.

Test: unittests
Change-Id: I1380cd0dbce6cb8f968b9e282da22417d18cb4b9

3 files changed