fix: SimpleVectorStoreFilterExpressionConverter incorrectly treats "in" substring inside metadata key as IN operator

[diydriller]

Summary

This PR fixes a substring–based bug in SimpleVectorStoreFilterExpressionConverter where metadata keys containing "in" were incorrectly interpreted as IN operators.

The fix ensures that only real IN / NOT IN operators trigger the contains() conversion logic.

Changes

Updated doValue() to detect true IN operators using more precise checks:

String ctx = context.toString().trim();
boolean isInClause = ctx.endsWith(" in");
boolean isNotInClause = ctx.endsWith(" not in");

if (!isInClause && !isNotInClause) {
    context.append(formattedList);
} else {
    appendSpELContains(formattedList, context);
}

Closes: #4908