[4.3.x] cherrypicks

[cdisselkoen]

Description of changes

Cherry-picks two commits to release/4.3.x:

• Assume sufficient stack space when it cannot be determined #1446
• clarify docs and changelog for 1446 #1457

Issue #, if available

Checklist for requesting a review

The change in this PR is (choose one, and delete the other options):

• A bug fix or other functionality change requiring a patch to cedar-policy.

I confirm that this PR (choose one, and delete the other options):

• Updates the "Unreleased" section of the CHANGELOG with a description of my change (required for major/minor version bumps).

I confirm that cedar-spec (choose one, and delete the other options):

• Does not require updates because my change does not impact the Cedar formal model or DRT infrastructure.

I confirm that docs.cedarpolicy.com (choose one, and delete the other options):

• Does not require updates because my change does not impact the Cedar language specification.

[cdisselkoen]

CI failures are unrelated -- CI fails to find a 4.3.x branch of cedar-java because there isn't one yet.