Remove dependency on CFE_PLATFORM_TLM_MID_BASE in tests

[jphickey]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I performed a cursory search to see if the bug report is relevant, not redundant, nor in conflict with other tickets.

Describe the bug
The MM app depends on CFE_PLATFORM_TLM_MID_BASE which may or may not exist in the user-defined config

To Reproduce
Build MM with latest mainline

Expected behavior
Should not depend on this symbol

System observed on:
Debian

Additional context
Unit test issue, does not affect FSW

Reporter Info
Joseph Hickey, Vantage Systems, Inc.