ci: Remove pytest-forked from requirements-testing.txt (#6611)

Remove the package from `requirements-testing.txt` and add it only as a dependency of the test suites that rely on it.
This is part of environment cleanup before moving the remaining testing dependencies to a uv dependency group.

Author: alexander-alderman-webb

requirements-testing.txt

@@ -1,7 +1,6 @@
 pytest>=6.0.0
 pytest-cov
 dataclasses; python_version < "3.7"
-pytest-forked
 executing
 asttokens
 responses

scripts/populate_tox/config.py

@@ -80,7 +80,7 @@
     "celery": {
         "package": "celery",
         "deps": {
-            "*": ["newrelic<10.17.0", "redis"],
+            "*": ["newrelic<10.17.0", "redis", "pytest-forked"],
             "py3.6": ["newrelic<8"],
             "py3.7": ["importlib-metadata<5.0"],
         },
@@ -107,6 +107,7 @@
                 "psycopg2-binary",
                 "djangorestframework",
                 "pytest-django",
+                "pytest-forked",
                 "Werkzeug",
                 "channels[daphne]",
             ],
@@ -185,7 +186,13 @@
     "grpc": {
         "package": "grpcio",
         "deps": {
-            "*": ["protobuf", "mypy-protobuf", "types-protobuf", "pytest-asyncio"],
+            "*": [
+                "protobuf",
+                "mypy-protobuf",
+                "types-protobuf",
+                "pytest-asyncio",
+                "pytest-forked",
+            ],
         },
         "python": ">=3.7",
     },
@@ -368,7 +375,7 @@
     "quart": {
         "package": "quart",
         "deps": {
-            "*": ["quart-auth", "pytest-asyncio", "Werkzeug"],
+            "*": ["quart-auth", "pytest-asyncio", "pytest-forked", "Werkzeug"],
             ">=0.19": ["quart-flask-patch"],
             "<0.19": [
                 "blinker<1.6",