Fix CARGO_HOME location for airflow user builds

[potiuk]

Move CARGO_HOME from /usr/local/cargo to /home/airflow/.cargo so that
cargo builds work correctly when running as the airflow user, avoiding
permission issues with the system-wide cargo directory.

---

Was generative AI tooling used to co-author this PR?

• Yes — Claude Code (Claude Opus 4.6)

Generated-by: Claude Code (Claude Opus 4.6) following the guidelines

[ramitkataria]

Tested this on x86 prod image and can confirm that it now builds successfully. Thanks!

[ramitkataria]

This fixes this error which was only occuring in x86 prod image builds:

#55 33.66   ├─▶ The build backend returned an error
#55 33.66   ╰─▶ Call to `maturin.build_wheel` failed (exit status: 1)
#55 33.66 
#55 33.66       [stdout]
#55 33.66       Running `maturin pep517 build-wheel -i
#55 33.66       /tmp/.cache/uv/builds-v0/.tmpYsX87f/bin/python --compatibility off`
#55 33.66 
#55 33.66       [stderr]
#55 33.66           Updating crates.io index
#55 33.66       warning: failed to write cache, path:
#55 33.66       /usr/local/cargo/registry/index/index.crates.io-1949cf8c6b5b557f/.cache/py/o3/pyo3,
#55 33.66       error: Permission denied (os error 13)
#55 33.66        Downloading crates ...
#55 33.66         Downloaded alloc-stdlib v0.2.2
#55 33.66       error: failed to create directory
#55 33.66       `/usr/local/cargo/registry/cache/index.crates.io-1949cf8c6b5b557f`
#55 33.66 
#55 33.66       Caused by:
#55 33.66         Permission denied (os error 13)
#55 33.66       💥 maturin failed
#55 33.66         Caused by: Cargo metadata failed. Does your crate compile with `cargo
#55 33.66       build`?
#55 33.66         Caused by: `cargo metadata` exited with an error:
#55 33.66       Error: command ['maturin', 'pep517', 'build-wheel', '-i',
#55 33.66       '/tmp/.cache/uv/builds-v0/.tmpYsX87f/bin/python', '--compatibility',
#55 33.66       'off'] returned non-zero exit status 1
#55 33.66 
#55 33.66       hint: This usually indicates a problem with the package or the build
#55 33.66       environment.
#55 33.66   help: `pyiceberg-core` (v0.9.0) was included because
#55 33.66         `apache-airflow-providers-common-sql:dev` (v1.34.0) depends on
#55 33.66         `pyiceberg-core`

The root cause of the issue seems to be a missing wheel for pyiceberg-core for x86 in version 0.9.0. This made it build it using cargo which had a permissions issue.

But now, with the new path for CARGO_HOME, that permissions issue during cargo build doesn't occur.