Remove 1.6.0-beta of core-test from pom files (Azure#19560)

Co-authored-by: JP Chen <jiach@microsoft.com>

Author: JianpingChen

sdk/communication/azure-communication-identity/pom.xml

@@ -97,7 +97,7 @@
     <dependency>
       <groupId>com.azure</groupId>
       <artifactId>azure-core-test</artifactId>
-      <version>1.6.0-beta.1</version> <!-- {x-version-update;com.azure:azure-core-test;current} -->
+      <version>1.5.3</version> <!-- {x-version-update;com.azure:azure-core-test;dependency} -->
       <scope>test</scope>
     </dependency>
     <dependency>

sdk/communication/azure-communication-phonenumbers/pom.xml

@@ -97,7 +97,7 @@
     <dependency>
       <groupId>com.azure</groupId>
       <artifactId>azure-core-test</artifactId>
-      <version>1.6.0-beta.1</version> <!-- {x-version-update;com.azure:azure-core-test;current} -->
+      <version>1.5.3</version> <!-- {x-version-update;com.azure:azure-core-test;dependency} -->
       <scope>test</scope>
     </dependency>
     <dependency>
@@ -115,7 +115,7 @@
     <dependency>
       <groupId>com.azure</groupId>
       <artifactId>azure-identity</artifactId>
-      <version>1.2.3</version> <!-- {x-version-update;com.azure:azure-identity;dependency} -->    
+      <version>1.2.3</version> <!-- {x-version-update;com.azure:azure-identity;dependency} -->
       <scope>test</scope>
     </dependency>
   </dependencies>