[roll] Roll fuchsia [bazel][python] Improve launcher script in toolchain

... by following symlinks to determine directory for the real
interpreter and library zip archive.

Newer versions of rules_python [0] create a .venv directory and symlink
the script into the directory. The fuchsia python prebuilt launcher
script will fail to find its accompanying files (like python3.11-real
and the lib zip) because it relied on $BASH_SOURCE[0] without resolving
the symlink.

This patch updates the python launcher generation to use realpath,
ensuring the script directory resolves to the original repository path
where the dependencies actually exist.

[0] https://rules-python.readthedocs.io/en/latest/changelog.html#v2-0-0

Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1677914
Original-Original-Revision: be56b47b629c251b728620830b88f6191640405d
GitOrigin-RevId: d85bbdcf94c00a8ed4188e156155322a430ef3a2
Change-Id: Ia6ab29bb2bdaa64f2542a4840f36fe1ec1777add
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1680603
Cr-Commit-Position: refs/heads/main@{#195583}