Native Auth E2E test generate email locally (#2570)

Make changes inside TemporaryEmailService.kt to generate random email
account locally.

Please refer to the MSAL PR:
AzureAD/microsoft-authentication-library-for-android#2244

Author: Yuki-YuXin

testutils/src/main/java/com/microsoft/identity/internal/testutils/nativeauth/api/TemporaryEmailService.kt

@@ -37,6 +37,7 @@ import java.time.LocalDateTime
 import java.time.ZoneOffset
 import java.time.ZonedDateTime
 import java.time.format.DateTimeFormatter
+import java.util.UUID
 
 
 /**
@@ -50,7 +51,12 @@ class TemporaryEmailService {
     private val retryDelayMs: Long = 4000
     private val newEmailCutoff = 5.0
 
-    fun generateRandomEmailAddress(): String {
+    fun generateRandomEmailAddressLocally(): String {
+        val randomId = UUID.randomUUID().toString().substring(0, 8)
+        return "native-auth-signup-$randomId@1secmail.org"
+    }
+
+    fun generateRandomEmailAddressWithAPI(): String {
         val generatedUsers = api.generateRandomEmailAddress()
         if (generatedUsers.isEmpty()) {
             throw ApiException("No generated users returned from TemporaryEmailApi")