Fix some ubsan issues related to double vs ui64 (#13364)

Author: snaury

ydb/core/sys_view/service/ext_counters.cpp

@@ -177,7 +177,7 @@ class TExtCountersUpdaterActor
                 ExecuteLatencyMsPrevValues[n] = value;
                 if (ExecuteLatencyMsBounds[n] == 0) {
                     NMonitoring::TBucketBound bound = snapshot->UpperBound(n);
-                    ExecuteLatencyMsBounds[n] = bound == Max<NMonitoring::TBucketBound>() ? Max<ui64>() : bound;
+                    ExecuteLatencyMsBounds[n] = bound == Max<NMonitoring::TBucketBound>() ? Max<ui64>() : ui64(bound);
                 }
             }
             metrics->AddMetric("queries.requests", total);

ydb/core/tablet_flat/ut/ut_stat.cpp

@@ -746,7 +746,7 @@ Y_UNIT_TEST_SUITE(BuildStatsHistogram) {
 
             ui32 operator()(const TRow&) noexcept
             {
-                auto x = Random.Uniform(1 << Buckets);
+                auto x = Random.Uniform(1, 1 << Buckets);
                 return Min(ui32(log2(x)), Buckets - 1);
             }