Add focused HQL renderer coverage for single-character string literals used as the left operand of collection membership predicates.

As a follow-up to #4278, I also checked the JPQL/EQL grammar change for unintended widening. The only meaningful new parse surface is the intended collection membership predicate shape (MEMBER OF/NOT MEMBER OF); common existing single-character literal positions such as comparisons, IN, constructors, LIKE, TRIM, functions, CASE, and update assignments continue to parse as before.

HQL does not share the same root cause because quoted strings are handled as STRING_LITERAL, without a separate single-character token. This PR leaves the HQL grammar unchanged and adds coverage for member of, not member of, subquery, update, and delete surfaces.

Verified with the HQL query renderer test suite.

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See #4278