Remove the use of ifdef for TESTING_BUILD in KeyVault clients, where (#5406)

they are not needed.

Author: ahsonkhan

sdk/keyvault/azure-security-keyvault-certificates/inc/azure/keyvault/certificates/certificate_client.hpp

@@ -34,7 +34,7 @@ namespace Azure { namespace Security { namespace KeyVault { namespace Certificat
    *
    * @details The client supports retrieving KeyVaultCertificate.
    */
-  class CertificateClient _azure_NON_FINAL_FOR_TESTS {
+  class CertificateClient final {
     friend class CreateCertificateOperation;
 
 #if defined(_azure_TESTING_BUILD)

sdk/keyvault/azure-security-keyvault-secrets/inc/azure/keyvault/secrets/secret_client.hpp

@@ -43,7 +43,7 @@ namespace Azure { namespace Security { namespace KeyVault { namespace Secrets {
    * Vault. The client supports creating, retrieving, updating, deleting, purging, backing up,
    * restoring, and listing the secret.
    */
-  class SecretClient _azure_NON_FINAL_FOR_TESTS {
+  class SecretClient final {
 
   private:
     // Using a shared pipeline for a client to share it with LRO (like delete key)