Fix several issues with testing system (#5394)

Fix https://github.com/opencv/cvat/issues/5214

1. Stable names for containers (_ vs -)
2. Improve documentation

site/content/en/docs/contributing/running-tests.md

@@ -42,7 +42,11 @@ yarn run cypress:run:chrome:canvas3d
 1. Install all necessary requirements before running REST API tests:
    ```
    pip install -r ./tests/python/requirements.txt
+   pip install -e ./cvat-sdk
+   pip install -e ./cvat-cli
    ```
+1. Stop any other CVAT containers which you run previously. They keep ports
+which are used by containers for the testing system.
 
 **Running tests**
 

tests/python/rest_api/__init__.py

@@ -0,0 +1,3 @@
+# Copyright (C) 2022 Intel Corporation
+#
+# SPDX-License-Identifier: MIT

tests/python/shared/fixtures/init.py

@@ -218,7 +218,9 @@ def start_services(rebuild=False):
         )
 
     _run(
-        f"docker-compose -p {PREFIX} "
+        # use compatibility mode to have fixed names for containers (with underscores)
+        # https://github.com/docker/compose#about-update-and-backward-compatibility
+        f"docker-compose -p {PREFIX} --compatibility "
         + "--env-file "
         + osp.join(CVAT_ROOT_DIR, "tests", "python", "webhook_receiver", ".env")
         + f" -f {' -f '.join(DC_FILES)} up -d "
@@ -264,7 +266,9 @@ def services(request):
 
         if stop:
             _run(
-                f"docker-compose -p {PREFIX} "
+                # use compatibility mode to have fixed names for containers (with underscores)
+                # https://github.com/docker/compose#about-update-and-backward-compatibility
+                f"docker-compose -p {PREFIX} --compatibility "
                 + "--env-file "
                 + osp.join(CVAT_ROOT_DIR, "tests", "python", "webhook_receiver", ".env")
                 + f" -f {' -f '.join(DC_FILES)} down -v",