Remove member type validation in group criteria

[annakhm]

This follows NSX allowing mixing some member types within same expression block, which was not allowed earlier.

Rather then following NSX validation for which member types mixes are permitted, terraform will let NSX do the validation for this part. Other validations on terraform side - such as same expression type - are not affected by this change.

[annakhm]

--- PASS: TestAccResourceNsxtPolicyGroup_empty (11.29s)
--- PASS: TestAccResourceNsxtPolicyGroup_mixedCriteria (21.04s)
--- PASS: TestAccResourceNsxtPolicyGroup_basicImport (24.25s)
--- PASS: TestAccResourceNsxtPolicyGroup_groupTypeIPAddressCriteria (33.46s)
--- PASS: TestAccResourceNsxtPolicyGroup_nestedCriteria (33.54s)
--- PASS: TestAccResourceNsxtPolicyGroup_multipleIPAddressCriteria (33.74s)
--- PASS: TestAccResourceNsxtPolicyGroup_multipleCriteria (34.56s)
--- PASS: TestAccResourceNsxtPolicyGroup_addressCriteria (34.64s)
--- PASS: TestAccResourceNsxtPolicyGroup_pathCriteria (50.44s)
--- PASS: TestAccResourceNsxtPolicyGroup_identityGroup (56.32s)
--- PASS: TestAccResourceNsxtPolicyGroup_multipleNestedCriteria (56.71s)

[annakhm]

--- PASS: TestAccResourceNsxtPolicyGroup_empty_multitenancy (8.41s)
--- PASS: TestAccDataSourceNsxtPolicyGroup_multitenancy (16.80s)
--- PASS: TestAccResourceNsxtPolicyGroup_basicImport_multitenancy (24.38s)
--- PASS: TestAccResourceNsxtPolicyGroup_addressCriteria_multitenancy (34.32s)