[RISC-V] De-intrinsify Min/MaxMagnitude

[tomeksowi]

Fallback to the library version, the generated version returned the lesser/greater magnitude instead of the original argument with such.

Part of #84834, cc @dotnet/samsung

[dotnet-policy-service]

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

[tomeksowi]

@risc-vv /run

[risc-vv]

RISC-V pull_request-CLR-QEMU: 9101 / 9131 (99.67%)

=======================
      passed: 9101
      failed: 2
     skipped: 591
      killed: 28
------------------------
 TOTAL tests: 9722
VIRTUAL time: 80h 42min 24s 237ms
   REAL time: 1h 19min 1s 481ms
=======================

report.xml, report.md, failures.xml, testclr_details.tar.zst

RISC-V pull_request-CLR-VF2: 9101 / 9131 (99.67%)

=======================
      passed: 9101
      failed: 2
     skipped: 591
      killed: 28
------------------------
 TOTAL tests: 9722
VIRTUAL time: 32h 0min 35s 150ms
   REAL time: 2h 7min 10s 321ms
=======================

report.xml, report.md, failures.xml, testclr_details.tar.zst

RISC-V pull_request-FX-QEMU: 0 / 1 (0.00%)

=======================
      passed: 0
      failed: 0
     skipped: 14
      killed: 1
------------------------
 TOTAL tests: 15
VIRTUAL time: 15s 444ms
   REAL time: 4h 30min 0s 487ms
=======================

report.xml, report.md, failures.xml, testclr_details.tar.zst

RISC-V pull_request-FX-VF2: 0 / 66 (0.00%)

=======================
      passed: 0
      failed: 0
     skipped: 14
      killed: 66
------------------------
 TOTAL tests: 80
VIRTUAL time: 1min 14s 522ms
   REAL time: 12h 30min 7s 384ms
=======================

report.xml, report.md, failures.xml, testclr_details.tar.zst

Build information and commands

GIT: 0d012b4d1be3ca4ebd5e3600f19920d644db105b
CI: d023c7d591ab286aa343d644f00b5daa59d8d6b0
REPO: dotnet/runtime
BRANCH: main
CONFIG: Checked
LIB_CONFIG: Release