MDEV-39276: Assertion 0 failed in json_find_path

[grooverdan]

This was resolved with MDEV-35548, however we add two additional test cases.

[gemini-code-assist]

Code Review

This pull request adds regression test cases for the JSON_EXISTS function, specifically targeting complex nested structures and range-based paths. The feedback suggests following the standard MariaDB practice of including a reference to the relevant MDEV task (MDEV-39276) within the test file to provide context for future maintenance.

[gemini-code-assist]

It is a standard practice in the MariaDB test suite to include a reference to the MDEV task (e.g., --echo # MDEV-39276) before adding regression test cases. This provides essential context for future maintenance, especially for complex or fuzzer-generated test cases like these. Note that the corresponding .result file will also need to be updated to reflect this change.

--echo # MDEV-39276
SELECT JSON_EXISTS('[[[[[Y[[[[n[[[[[[[[[[[n[[[Vn]]]]]]]]]]]]]],]]:]]]](', '$[0 to rrrrrRR-1]') as je;
SELECT JSON_EXISTS('[[[[[Y[[[[[[[[[[[[[[[[[[Vn]]]]]]]]]]]]]],]]:]]]](', '$[0 to rrrrRR-1]') as je;