Refactor test files to use dynamic resource group names

[mattdot]

This pull request introduces changes to the test files in the internal/services/licensing directory to ensure unique resource group names by appending a random number. The most important changes involve modifying the resource group names in various test functions and importing necessary packages.

Test Function Updates:

• internal/services/licensing/datasource_billing_policies_environments_test.go: Updated TestAccBillingPoliciesEnvironmentsDataSource_Validate_Read to append a random number to the resource group name using strconv.Itoa(rand.IntN(9999)).
• internal/services/licensing/datasource_billing_policies_test.go: Updated TestAccBillingPoliciesDataSource_Validate_Read to append a random number to the resource group name.
• internal/services/licensing/resource_billing_policy_environment_test.go: Updated several functions (TestAccBillingPolicyResourceEnvironment_Validate_Create, TestAccBillingPolicyResourceEnvironment_Validate_Update) to use a random number in the resource group name. [1] [2] [3] [4]
• internal/services/licensing/resource_billing_policy_test.go: Updated multiple functions (TestAccBillingPolicyResource_Validate_Create, TestAccBillingPolicy_Validate_Update, TestAccBillingPolicy_Validate_Update_ForceRecreate) to use a random number in the resource group name. [1] [2] [3] [4]

Package Imports:

• Added math/rand/v2 and strconv imports to several test files to facilitate the generation of random numbers for resource group names. [1] [2] [3] [4]

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 76.26%. Comparing base (e153201) to head (4ffc078). Report is 9 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #483 +/- ## ========================================== - Coverage 76.38% 76.26% -0.13% ========================================== Files 98 98 Lines 11207 11246 +39 ========================================== + Hits 8561 8577 +16 - Misses 2048 2060 +12 - Partials 598 609 +11 ```

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