remove duckdb object cache integration

[myrrc]

#6652 makes Duckdb use
Vortex cache instead of its own cache. Object cache in Duckdb isn't used
anywhere except for tests.

[codspeed-hq]

Merging this PR will improve performance by 26.44%

⚡ 5 improved benchmarks
✅ 995 untouched benchmarks
⏩ 1466 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	patched_take_10k_contiguous_patches	2.3 ms	2.1 ms	+10.81%
⚡	Simulation	patched_take_200k_dispersed	5.6 ms	4.7 ms	+19.88%
⚡	Simulation	patched_take_200k_first_chunk_only	5.4 ms	4.8 ms	+11.99%
⚡	Simulation	take_200k_dispersed	4.5 ms	3.6 ms	+24.36%
⚡	Simulation	take_200k_first_chunk_only	4.2 ms	3.3 ms	+26.44%

---

_{Comparing myrrc/rm-duckdb-object-cache (949a4ee) with develop (dfe3699)}

Footnotes

1. 1466 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩