GHA/linux: move mbedTLS and wolfSSL valgrind jobs to arm64

GHA/linux: move mbedTLS and wolfSSL valgrind jobs to arm64

For significantly better performance.

AM wolfssl-opensslextra valgrind 1:  6m53s -> 4m15s
AM wolfssl-opensslextra valgrind 2:  6m47s -> 4m25s
CM mbedtls gss valgrind 1:           8m33s -> 4m31s
CM mbedtls gss valgrind 2:           8m39s -> 4m34s
('after' times corrected for 'install prereq' differences)

before: https://github.com/curl/curl/actions/runs/21255607562
after: https://github.com/curl/curl/actions/runs/21257368016

Also tried rustls, but that'd require linux arm64 release binaries at:
https://github.com/rustls/rustls-ffi/releases

Closes #20392