Move ci_exec to the Python script

The Bash script was acceptable, but CI_EXEC_CMD_PREFIX was a single
string, relying on brittle word splitting that the shellcheck SC2086
would warn about.

So just fix that by moving everything to the Python script and deleting
the Bash script.

This also removes the need to export the CI_CONTAINER_ID env var.

ci/test/02_run_container.py

@@ -162,9 +162,28 @@ def main():
             stdout=subprocess.PIPE,
             text=True,
         ).stdout.strip()
-        os.environ["CI_CONTAINER_ID"] = container_id
 
-    run(["./ci/test/02_run_container.sh"])  # run the remainder
+    def ci_exec(cmd_inner, **kwargs):
+        if os.getenv("DANGER_RUN_CI_ON_HOST"):
+            prefix = []
+        else:
+            prefix = ["docker", "exec", container_id]
+
+        return run([*prefix, *cmd_inner], **kwargs)
+
+    # Normalize all folders to BASE_ROOT_DIR
+    ci_exec([
+        "rsync",
+        "--recursive",
+        "--perms",
+        "--stats",
+        "--human-readable",
+        f"{os.environ['BASE_READ_ONLY_DIR']}/",
+        f"{os.environ['BASE_ROOT_DIR']}",
+    ])
+    ci_exec([f"{os.environ['BASE_ROOT_DIR']}/ci/test/01_base_install.sh"])
+    ci_exec([f"{os.environ['BASE_ROOT_DIR']}/ci/test/03_test_script.sh"])
+
     if not os.getenv("DANGER_RUN_CI_ON_HOST"):
         print("Stop and remove CI container by ID")
         run(["docker", "container", "kill", container_id])