fix: make Enabled within RulesetRuleActionParametersCategories optional for DDoS L7 phase

[Quentin-M]

Description

As per the API response while configuring ruleset category override in ddos_l7, the Enabled field cannot be used:
DDoS L7 overrides cannot use the enabled field, DDoS L7 overrides cannot use the enabled field

Therefore, this commit makes the field optional.

    "overrides": {
     "categories": [
      {
       // INVALID
       "category": "unusual-requests",
       "action": "challenge",
       "enabled": false
      },
      {
       // VALID
       "category": "botnets",
       "action": "challenge",
      }
     ],

Has your change been tested?

The change was tested within cloudflare/terraform-provider-cloudflare via a nacceptance test as well as by running the provider itself within Terraform.

Types of changes

What sort of change does your code introduce/modify?

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• Unclear to me at this time where a documentation change might be required.
• Have not identified any relevant test associated with this structure after doing a quick code search.

[jacobbednarz]

appreciate this @Quentin-M!