chore(ci): Clarify the testing scenario

Being in the middle, the "test all" case isn't as obvious nor the
exceptions to it.

This also ensures that the packages lower in the stack get tested before
those higher in the stack, hopefully providing more actionable failures.

Author: epage

.github/workflows/main.yml

@@ -151,7 +151,8 @@ jobs:
       run: echo CARGO_CONTAINER_TESTS=1 >> $GITHUB_ENV
       if: matrix.os == 'ubuntu-latest'
 
-    - run: cargo test -p cargo
+    # `benchsuite`, and some specific `cargo` cases, will be tested later
+    - run: cargo test --exclude benchsuite
     - name: Clear intermediate test output
       run: ci/clean-test-output.sh
 
@@ -170,7 +171,6 @@ jobs:
       run: 'cargo test -p cargo --test testsuite -- fix::'
       env:
         __CARGO_TEST_FORCE_ARGFILE: 1
-    - run: cargo test --exclude cargo --exclude benchsuite
     - name: Check benchmarks
       run: |
         # This only tests one benchmark since it can take over 10 minutes to