fix: Remove --no-build-isolation from pip install command (#2360)

Fixes #2328.

In #2126, we discussed and added `--no-build-isolation` to ensure that
sdist builds pulled from rules_python supplied dependencies. An
unanticipated/misunderstood side-effect of this is that pip will no
longer resolve necessary, declared build time dependencies from a
package index. That's a significant point of friction for users, and,
it's much harder to opt-out of the behavior than to opt-in given the
presence of `extra_pip_args`.

CHANGELOG.md

@@ -33,6 +33,10 @@ A brief description of the categories of changes:
   ([2310](https://github.com/bazelbuild/rules_python/issues/2310)).
 * (publish) The dependencies have been updated to the latest available versions
   for the `twine` publishing rule.
+* (whl_library) Remove `--no-build-isolation` to allow non-hermetic sdist builds
+  by default. Users wishing to keep this argument and to enforce more hermetic
+  builds can do so by passing the argument in
+  [`pip.parse#extra_pip_args`](https://rules-python.readthedocs.io/en/latest/api/rules_python/python/extensions/pip.html#pip.parse.extra_pip_args)
 
 {#v0-0-0-fixed}
 ### Fixed

python/private/pypi/whl_library.bzl

@@ -230,7 +230,7 @@ def _whl_library_impl(rctx):
             # and, allow getting build dependencies from PYTHONPATH, which we
             # setup in this repository rule, but still download any necessary
             # build deps from PyPI (e.g. `flit_core`) if they are missing.
-            extra_pip_args.extend(["--no-build-isolation", "--find-links", "."])
+            extra_pip_args.extend(["--find-links", "."])
 
     args = _parse_optional_attrs(rctx, args, extra_pip_args)