schemeshard: fix enable_alter_database_create_hive_first mode (ydb-platform#10074)

Storage pools duplication (in memory only) happened at the first database alter (first alter is actually constructs the database) causes StatusInvalidParameter errors for the next alters if they repeat storage pools specification. Ydbcp does exactly that and so databases created via ydbcp are displayed in the webui as having CONFIGURING state instead of RUNNING.

Databases stuck in that state are actually fully functional, but still are not being able to execute some alters until root schemeshard is rebooted.

KIKIMR-10367
YDBOPS-7628

Author: ijon

ydb/core/tx/schemeshard/schemeshard__operation_alter_extsubdomain.cpp

@@ -936,21 +936,23 @@ class TAlterExtSubDomain: public TSubOperation {
         // Create or derive alter.
         // (We could have always created new alter from a current subdomainInfo but
         // we need to take into account possible version increase from CreateHive suboperation.)
-        auto createAlterFrom = [&inputSettings, &delta](auto prototype) {
+        auto createAlterFrom = [&inputSettings](auto prototype, const TStoragePools& additionalPools) {
             return MakeIntrusive<TSubDomainInfo>(
                 *prototype,
                 inputSettings.GetPlanResolution(),
                 inputSettings.GetTimeCastBucketsPerMediator(),
-                delta.StoragePoolsAdded
+                additionalPools
             );
         };
         TSubDomainInfo::TPtr alter = [&delta, &subdomainInfo, &createAlterFrom, &context]() {
             if (delta.AddExternalHive && context.SS->EnableAlterDatabaseCreateHiveFirst) {
                 Y_ABORT_UNLESS(subdomainInfo->GetAlter());
-                return createAlterFrom(subdomainInfo->GetAlter());
+                //NOTE: existing alter already has all storage pools that combined operation wanted to add,
+                // should not add them second time when deriving alter from alter
+                return createAlterFrom(subdomainInfo->GetAlter(), {});
             } else {
                 Y_ABORT_UNLESS(!subdomainInfo->GetAlter());
-                return createAlterFrom(subdomainInfo);
+                return createAlterFrom(subdomainInfo, delta.StoragePoolsAdded);
             }
         }();