Fix CDM "primary" tag in CTS tests

Use the correct "android.companion.primary" tag in the declaration of
PrimaryCompanionService in cts-companion-common module.

Bug: 198539218
Test: atest CtsCompanionDeviceManagerCoreTestCases
Test: atest CtsCompanionDeviceManagerUiAutomationTestCases
Change-Id: Idbe4985fb0482357aff5be77a713cc5d751d3053
diff --git a/tests/tests/companion/common/AndroidManifest.xml b/tests/tests/companion/common/AndroidManifest.xml
index 87acf92..6a9a3bc 100644
--- a/tests/tests/companion/common/AndroidManifest.xml
+++ b/tests/tests/companion/common/AndroidManifest.xml
@@ -33,7 +33,7 @@
             </intent-filter>
 
             <meta-data
-                    android:name="primary"
+                    android:name="android.companion.primary"
                     android:value="true" />
         </service>