fix: add DiffSuppressFunc to compare lists in GPU configuration

[kasia-kujawa]

Following issue was observed:

Terraform read a state as zero values but they were nils, and then changes were visible even when no changes were added in NodeTemplate.
In such old and new values were the same internally:

 old ([]interface {}) (len=1 cap=1) {
	 (map[string]interface {}) (len=3) {
	  (string) (len=19) "enable_time_sharing": (bool) false,
	  (string) (len=30) "default_shared_clients_per_gpu": (int) 0,
	  (string) (len=21) "sharing_configuration": ([]interface {}) {
	  }
	 }
	}
new ([]interface {}) (len=1 cap=1) {
	 (map[string]interface {}) (len=3) {
	  (string) (len=19) "enable_time_sharing": (bool) false,
	  (string) (len=30) "default_shared_clients_per_gpu": (int) 0,
	  (string) (len=21) "sharing_configuration": ([]interface {}) {
	  }
	 }
	}

but Terraform presented it differently.

• In Terraform nil values for optional attributes are serialized as zero values.
• When you read the state, the value is shown as 0, but it's actually unset; Terraform treats missing or unset optional attributes as zero values by default.
• There is general problem with detecting changes in Terraform lists, this merge requests add custom comparison of lists, example issue in Terraform SDK: DiffSuppressFunc doesn't work for list-type attributes hashicorp/terraform-plugin-sdk#477

I removed changes gpu configuration from basic test as this test without gpu configuration will detect if any changes remains after applying the configuration when gpu is not configured.