[FEA] Migrate left join and conditional join benchmarks to use nvbench

[PointKernel]

Is your feature request related to a problem? Please describe.
The current left join and conditional join benchmarks are still using gbench. We should migrate them to use nvbench for simplicity and consistency.

Describe the solution you'd like

TODO:

• Migrate from gbench to nvbench
• Similar to Clean up join benchmarks #15644, use JOIN_KEY_TYPE_RANGE, JOIN_NULLABLE_RANGE and JOIN_SIZE_RANGE to reduce the number of test cases and simplify the implementation
• Get rid of the dispatching between gbench and nvbench in join_common.hpp