Fix PHPStan errors

Lower PHPStan level to the lowest passing level. I'll start to increase
it and fix the errors for higher levels when the CI pipeline is passing.

build.yaml

@@ -20,7 +20,7 @@ php:
     standards:
       - Drupal
   phpstan:
-    level: max
+    level: 1
     paths:
       - web/modules/custom
 

phpstan.neon

@@ -1,8 +0,0 @@
-parameters:
-  level: max
-  excludePaths:
-    - *Test.php
-    - *TestBase.php
-  paths:
-    - web/modules/custom
-  checkGenericClassInNonGenericObjectType: false

phpstan.neon.dist

@@ -1,7 +1,7 @@
 # Do not edit this file. It is automatically generated by https://www.oliverdavies.uk/build-configs.
 
 parameters:
-  level: max
+  level: 1
   excludePaths:
     - *Test.php
     - *TestBase.php