fix(ddl): MCOL-5974 TIMESTAMP columns are not IS NOT NULL by default in MCS (#3670)

The old behavior was to assign TIMESTAMP columns an IS NOT NULL
constraint if list of constraints was empty. Apparently, this particular
invariant was changed in 11.4 and bugfixes' mcol-5480.test started to
fail.

This patch fixes behavioral difference and reenables mcol-5480 test in
11.4.

dbcon/mysql/ha_mcs_ddl.cpp

@@ -867,12 +867,14 @@ int ProcessDDLStatement(string& ddlStatement, string& schema, const string& /*ta
           return rc;
         }
 
+#if MYSQL_VERSION_ID < 110400
         // For TIMESTAMP, if no constraint is given, default to NOT NULL
         if (createTable->fTableDef->fColumns[i]->fType->fType == ddlpackage::DDL_TIMESTAMP &&
             createTable->fTableDef->fColumns[i]->fConstraints.empty())
         {
           createTable->fTableDef->fColumns[i]->fConstraints.push_back(new ColumnConstraintDef(DDL_NOT_NULL));
         }
+#endif
 
         if (createTable->fTableDef->fColumns[i]->fDefaultValue)
         {

dbcon/mysql/ha_mcs_execplan.cpp

@@ -6292,7 +6292,7 @@ int processLimitAndOffset(SELECT_LEX& select_lex, gp_walk_info& gwi, SCSEP& csep
 // for the first column of the index if any.
 // Statistics is stored in GWI context.
 // Mock for ES 10.6
-#if MYSQL_VERSION_ID >= 110401
+#if MYSQL_VERSION_ID >= 120401
 void extractColumnStatistics(Item_field* ifp, gp_walk_info& gwi)
 {
   for (uint j = 0; j < ifp->field->table->s->keys; j++)

mysql-test/columnstore/bugfixes/mcol-5480.test

@@ -2,7 +2,6 @@
 # MCOL-5480 LDI loads values incorrectly for MEDIUMINT, TIME and TIMESTAMP
 # when cpimport is used for batch insert
 #
---source ../include/disable_11.4.inc
 --source ../include/have_columnstore.inc
 --source ../include/detect_maxscale.inc