Remove unused functions and files from STM core

[kuqin12]

Description

Removed unused files and functions from the STM core.

• [x] Impacts functionality?
  • Functionality - Does the change ultimately impact how firmware functions?
  • Examples: Add a new library, publish a new PPI, update an algorithm, ...
• [x] Impacts security?
  • Security - Does the change have a direct security impact on an application, flow, or firmware?
  • Examples: Crypto algorithm change, buffer overflow fix, parameter validation improvement, ...
• [ ] Breaking change?
  • Breaking change - Will anyone consuming this change experience a break in build or boot behavior?
  • Examples: Add a new library class, move a module to a different repo, call a function in a new library class in a pre-existing module, ...
• [ ] Includes tests?
  • Tests - Does the change include any explicit test code?
  • Examples: Unit tests, integration tests, robot tests, ...
• [ ] Includes documentation?
  • Documentation - Does the change contain explicit documentation additions outside direct code modifications (and comments)?
  • Examples: Update readme file, add feature readme file, link to documentation on an a separate Web page, ...

How This Was Tested

This change is not tested in the context of STM core as it is not invoked yet. The only validation is pipeline build.

Integration Instructions

N/A

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Please upload report for BASE (feature/spam@a3801b3). Learn more about missing BASE report.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## feature/spam #314 +/- ## ============================================== Coverage ? 0.46% ============================================== Files ? 144 Lines ? 22350 Branches ? 60 ============================================== Hits ? 105 Misses ? 22240 Partials ? 5 ``` | [Flag](https://app.codecov.io/gh/microsoft/mu_feature_mm_supv/pull/314/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=microsoft) | Coverage Δ | | |---|---|---| | [MmSupervisorPkg](https://app.codecov.io/gh/microsoft/mu_feature_mm_supv/pull/314/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=microsoft) | `0.46% <ø> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=microsoft#carryforward-flags-in-the-pull-request-comment) to find out more.

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