Postresql java mitigate break (#40416)

* Mitigate Java SDK breaks: rename PostgreSqlFlexibleServerHighAvailabilityMode back to HighAvailabilityMode

* use the old HighAvailabilityMode

Author: weidongxu-microsoft

specification/postgresql/DBforPostgreSQL.Management/client.tsp

@@ -31,3 +31,16 @@ using Azure.ClientGenerator.Core;
   "java"
 );
 @@clientName(RequestIdResponseHeader.requestId, "xMsRequestId", "java");
+
+@@clientName(Microsoft.DBforPostgreSQL.PostgreSqlFlexibleServerHighAvailabilityMode,
+  "HighAvailabilityMode",
+  "java"
+);
+@@clientName(Microsoft.DBforPostgreSQL.HighAvailabilityMode,
+  "SupportedHighAvailabilityMode",
+  "java"
+);
+@@alternateType(Microsoft.DBforPostgreSQL.ServerSkuCapability.supportedHaMode,
+  PostgreSqlFlexibleServerHighAvailabilityMode[],
+  "java"
+);