Switch from `VALUE` column name in TCK to `TEST_VALUE` to avoid keyword clashes

[Greg L. Turnquist]

H2 has declared "VALUE" a reserved word.

To ease maintaining TCK compliance, can we migrate to "TEST_VALUE" as the column name? There is some degree of risk for data stores that have overridden parts of TestKit or extended it and written custom code based upon "VALUE".

But it's an even bigger impact on r2dbc-h2 if we have to essentially, override the whole thing.

[Mark Paluch]

That makes sense on its own to move towards column/table names that are not clashing with keywords.