Add and apply Naming/RescuedExceptionsVariableName rubocop rule

This rule was introduced in RuboCop 0.67.2, but now after seeing a fix in version 1.65.1,
we have decided to add it. The reason for adding it is to ensure consistency in how we
reference exceptions throughout the project, by following a standard naming convention
for exception variables.

.rubocop.yml

@@ -337,6 +337,9 @@ Naming/BlockForwarding:
     - "app/controllers/management/base_controller.rb"
     - "app/controllers/subscriptions_controller.rb"
 
+Naming/RescuedExceptionsVariableName:
+  Enabled: true
+
 Naming/VariableName:
   Enabled: true