tests: move "venv" to "build-root" directory from "test" directory

Type: refactor

- refactored VPP test code to remove "ignore_path" variable
  from "discover_tests" function and "run_test" code
- configured VPP test makefile, config file, and 'run.sh' shell script
  to move "venv" directory from "test" dir to "build-root" dir

Signed-off-by: Saima Yunus <yunus.saima.234@gmail.com>
Change-Id: Id2beecbb99f24ce13ed118a1869c5adbef247e50

test/config.py

@@ -395,7 +395,7 @@ config.test_src_dir = test_dirs
 
 
 if config.venv_dir is None:
-    config.venv_dir = f"{ws}/test/venv"
+    config.venv_dir = f"{ws}/build-root/test/venv"
 
 if config.failed_dir is None:
     config.failed_dir = f"{config.tmp_dir}"