Handle buffer allocation failure in `prvCreateSectors`

[tony-josi-aws]

Description

This PR fixes an ignored memory allocation failure in prvCreateSectors by checking the return values and passing them to caller APIs. Thanks, @hlef for reporting this issue in #1149.

Test Steps

PR tests: HW tests on STM32F4 DUT: with device as both TCP client and server CI demo runs: https://github.com/tony-josi-aws/FreeRTOS/actions/runs/9383436139/job/25837038341

Checklist:

• [x] I have tested my changes. No regression in existing tests.
• [x] I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

1149

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