How to reproduce:
1. Build the attached project for iOS platform.
2. Open the Xcode project
3. Select Build Settings in Xcode
4. Search for "CODE_SIGN_ENTITLEMENTS"
5. Notice that entitlements file generated by notifications package is used (instead of user's one)

Actual result: Mobile Notification package rewrites the entitlements file.
Expected result: The entitlements file is not rewrote.

Reproducible with: 2018.4.17f1 (1.0.3), 2019.2.20f1 (preview.9 - 1.0.4), 2019.3.2f1 (preview.9 - 1.0.4).
Not reproducible with: 2020.1.0a24 (preview.9 - 1.0.4).

Notes:
- For some reason the issue doesn't reproduce on Unity 2020.1