Replace config/project repos with config/untrusted projects

The config-repo / project-repo terminology is confusing and we've
generally been using trusted-project and untrusted-project instead.
The term "untrusted-project" is straightforward, but "trusted-project"
is a little misleading, since there are other characteristics which
define it (notably, that the configuration held in it is branchless).
A better term for that might be "config-project".

Since the main config now directly refers to projects rather than
repos, complete the transition by replacing all config-repo
occurances with config-project and likewise project-repo with
untrusted-project.

Change-Id: I2341aa94e3622e2647b0506b78bc84dbcdec1901
Story: 2000953
diff --git a/tests/fixtures/config/duplicate-pipeline/main.yaml b/tests/fixtures/config/duplicate-pipeline/main.yaml
index 5e1bc6e..d28df0d 100755
--- a/tests/fixtures/config/duplicate-pipeline/main.yaml
+++ b/tests/fixtures/config/duplicate-pipeline/main.yaml
@@ -2,7 +2,7 @@
     name: tenant-duplicate
     source:
       gerrit:
-        config-repos:
+        config-projects:
           - common-config
-        project-repos:
+        untrusted-projects:
           - org/project