CNDB-13375 don't use keyspace name length in error message (#1639)

Part of riptano/cndb#13375

### What is the issue

Using keyspace name length in the error message for too long table name
is confusing, since the length might include CNDB's generated prefix
invisible to users.

### What does this PR fix and why was it fixed

Reformulates the error message for too long table name to avoid using
the keyspace name length, since it might contain CNDB generated prefix,
which is not visible to users.

Author: k-rus

src/java/org/apache/cassandra/cql3/statements/schema/CreateTableStatement.java

@@ -110,8 +110,8 @@ public void validate(QueryState state)
         super.validate(state);
 
         if (!state.getClientState().isInternal && tableName.length() > SchemaConstants.NAME_LENGTH - keyspaceName.length())
-            throw ire("Keyspace and table names combined shouldn't be more than %s characters long (got keyspace of %s chars and table of %s chars for %s.%s)",
-                      SchemaConstants.NAME_LENGTH, keyspaceName.length(), tableName.length(), keyspaceName, tableName);
+            throw ire("Table name is too long, it needs to fit %s characters (got table name of %s chars for %s.%s)",
+                      SchemaConstants.NAME_LENGTH - keyspaceName.length(), tableName.length(), keyspaceName, tableName);
 
         // Some tools use CreateTableStatement, and the guardrails below both don't make too much sense for tools and
         // require the server to be initialized, so skipping them if it isn't.

test/unit/org/apache/cassandra/schema/CreateTableValidationTest.java

@@ -113,8 +113,8 @@ public void failCreatingNewTableWithLongName()
                                                    "key int PRIMARY KEY," +
                                                    "val int)",
                                                    KEYSPACE, table)))
-        .withMessageContaining(String.format("Keyspace and table names combined shouldn't be more than %s characters long (got keyspace of %s chars and table of %s chars for %s.%s)",
-                                             SchemaConstants.NAME_LENGTH, KEYSPACE.length(), table.length(), KEYSPACE, table));
+        .withMessageContaining(String.format("Table name is too long, it needs to fit %s characters (got table name of %s chars for %s.%s)",
+                                             SchemaConstants.NAME_LENGTH - KEYSPACE.length(), table.length(), KEYSPACE, table));
     }
 
     @Test