Simplify PPCB E2E diagnostics test to verify unconditional clientCfgs keys

The partitionLevelCircuitBreakerCfg field now appears in clientCfgs for every
client regardless of PPCB configuration, so the E2E test no longer sets the
COSMOS.PARTITION_LEVEL_CIRCUIT_BREAKER_CONFIG system property. It just builds a
plain client and asserts all expected clientCfgs keys (including
partitionLevelCircuitBreakerCfg) are present in CosmosDiagnostics.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: jeet1995

sdk/cosmos/azure-cosmos-tests/src/test/java/com/azure/cosmos/PerPartitionCircuitBreakerE2ETests.java

@@ -4616,23 +4616,16 @@ public void validateHandlingOnNullPartitionKeyRangeOnSmallE2ETimeout_allOps(Oper
     /**
      * Regression validation for the Per-Partition Circuit Breaker (PPCB) diagnostics fix (see PR 49734).
      *
-     * When PPCB is explicitly enabled via the {@code COSMOS.PARTITION_LEVEL_CIRCUIT_BREAKER_CONFIG}
-     * system property, the {@code clientCfgs} section of the emitted {@link CosmosDiagnostics} must
-     * include the {@code partitionLevelCircuitBreakerCfg} field. A prior regression silently dropped
-     * this field. This test asserts that all the expected {@code clientCfgs} keys - including
-     * {@code partitionLevelCircuitBreakerCfg} - are present in the diagnostics of a real operation.
+     * The {@code clientCfgs} section of the emitted {@link CosmosDiagnostics} must always include the
+     * {@code partitionLevelCircuitBreakerCfg} field for every client, regardless of whether PPCB is
+     * explicitly enabled. A prior regression silently dropped this field unless PPAF mandated it. This
+     * test asserts that all the expected {@code clientCfgs} keys - including
+     * {@code partitionLevelCircuitBreakerCfg} - are present in the diagnostics of a real operation
+     * without setting any PPCB configuration.
      */
     @Test(groups = { "circuit-breaker-misc-gateway", "circuit-breaker-misc-direct", "circuit-breaker-read-all-read-many", "multi-region", "fi-thinclient-multi-master" }, timeOut = TIMEOUT)
     public void partitionLevelCircuitBreakerConfigIsPresentInClientCfgsDiagnostics() {
 
-        System.setProperty(
-            "COSMOS.PARTITION_LEVEL_CIRCUIT_BREAKER_CONFIG",
-            "{\"isPartitionLevelCircuitBreakerEnabled\": true, "
-                + "\"circuitBreakerType\": \"CONSECUTIVE_EXCEPTION_COUNT_BASED\","
-                + "\"consecutiveExceptionCountToleratedForReads\": 10,"
-                + "\"consecutiveExceptionCountToleratedForWrites\": 5,"
-                + "}");
-
         try (CosmosAsyncClient client = getClientBuilder().buildAsyncClient()) {
 
             CosmosAsyncContainer container = client
@@ -4653,7 +4646,8 @@ public void partitionLevelCircuitBreakerConfigIsPresentInClientCfgsDiagnostics()
                 .as("clientCfgs section should be present in the CosmosDiagnostics")
                 .contains("\"clientCfgs\"");
 
-            // All the clientCfgs keys unconditionally emitted by DiagnosticsClientConfigSerializer.
+            // All the clientCfgs keys unconditionally emitted by DiagnosticsClientConfigSerializer,
+            // including partitionLevelCircuitBreakerCfg (the field the regression previously dropped).
             List<String> expectedClientCfgsKeys = Arrays.asList(
                 "id",
                 "machineId",
@@ -4667,20 +4661,14 @@ public void partitionLevelCircuitBreakerConfigIsPresentInClientCfgsDiagnostics()
                 "consistencyCfg",
                 "proactiveInitCfg",
                 "e2ePolicyCfg",
-                "sessionRetryCfg");
+                "sessionRetryCfg",
+                "partitionLevelCircuitBreakerCfg");
 
             for (String expectedKey : expectedClientCfgsKeys) {
                 assertThat(diagnosticsString)
                     .as("clientCfgs key '%s' should be present in the CosmosDiagnostics", expectedKey)
                     .contains("\"" + expectedKey + "\"");
             }
-
-            // The regression fix: PPCB config must be present in clientCfgs when explicitly enabled.
-            assertThat(diagnosticsString)
-                .as("partitionLevelCircuitBreakerCfg should be present in clientCfgs when PPCB is enabled")
-                .contains("\"partitionLevelCircuitBreakerCfg\"");
-        } finally {
-            System.clearProperty("COSMOS.PARTITION_LEVEL_CIRCUIT_BREAKER_CONFIG");
         }
     }