pyiceberg-core: create even smaller artifacts (#1844)

## Which issue does this PR close?

- Closes #1839

## What changes are included in this PR?
use `lto = "thin", opt-level = "z"`

Tested building the wheel locally on mac. And this is the winning
combination.

Change                  | Wheel Size | Build Time | Notes
------------------------|------------|------------|------------------
fat LTO, opt-level=3 (default)    | 21 MB      | ~3 min     | Original
fat LTO, opt-level=z    | 12 MB      | ~3 min     | 43% smaller
thin LTO, opt-level=z | 12 MB | ~1.5 min | Same size, 2x faster build!
no LTO, opt-level=z     | 13 MB      | ~1 min     | Slightly bigger

### Size Reduction
[This
branch](https://github.com/apache/iceberg-rust/actions/runs/19285828822)
vs [main branch w/
#1841](https://github.com/apache/iceberg-rust/actions/runs/19280546898/attempts/1)

| Name | Old Size | New Size | % Decrease |

|-----------------------------------------------|----------|----------|------------|
| wheels-macos-latest-universal2-apple-darwin | 44.4 MB | 23.5 MB |
47.07% |
| wheels-ubuntu-latest-aarch64 | 66.1 MB | 40.9 MB | 38.12% |
| wheels-ubuntu-latest-armv7l | 70.5 MB | 33.1 MB | 53.05% |
| wheels-ubuntu-latest-x86_64 | 23.8 MB| 13 MB | 45.38% |
| wheels-windows-latest | 25.9 MB | 12.7 MB | 45.38% |
| wheels-sdist                                 | 575 KB   | 574 KB  

## Are these changes tested?

Yes 
https://github.com/apache/iceberg-rust/actions/runs/19285828822

Author: kevinjqliu

bindings/python/Cargo.toml

@@ -41,5 +41,6 @@ tokio = { version = "1.46.1", default-features = false }
 [profile.release]
 codegen-units = 1
 debug = false
-lto = "fat"
+lto = "thin"
+opt-level = "z"
 strip = true