[Cherry-Pick][Rebase & FF] UefiCpuPkg: Consume PcdCpuSmmApSyncTimeout2.

Description

In addition to what was said in the Cherry-Pick in #1096.

It looks like Edk2 picked up these changes, reverted them, and then added them back because Ovmf packages had already started consuming them.

The changes should not impact existing platforms, because the changes only modify PiSmmCpuDxeSmm.

[x] Impacts functionality?
- Functionality - Does the change ultimately impact how firmware functions?
- Examples: Add a new library, publish a new PPI, update an algorithm, ...
[ ] 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, ...

Local CI.

N/A