JIT: Pick some low-hanging fruit in physical promotion throughput (#86792)

JIT: Pick some low-hanging fruit in physical promotion throughput (#86792)

* Skip any IR traversals entirely if there are no candidates locals for
  physical promotion
* During accounting, do a quick pre-check for candidates in each
  statement using the linked locals list, before doing the tree walk.

Result:
```
Collection                                       PDIFF
aspnet.run.windows.x64.checked.mch              -0.59%
benchmarks.run.windows.x64.checked.mch          -0.65%
benchmarks.run_pgo.windows.x64.checked.mch      -0.65%
benchmarks.run_tiered.windows.x64.checked.mch   -0.65%
coreclr_tests.run.windows.x64.checked.mch       -0.66%
libraries.crossgen2.windows.x64.checked.mch     -0.61%
libraries.pmi.windows.x64.checked.mch           -0.63%
libraries_tests.pmi.windows.x64.checked.mch     -0.68%
```