[3.14] gh-134557: Suppress immortalization in _PyCode_GetScriptXIData under free-threading (gh134738)

Disable immortalization around Py_CompileString*().

The same approach as 332356b that fixed the refleaks in compile() and eval().

E: 09e72cf can pass test_capi, test_sys and test__interpchannels with this patch for me.

(cherry picked from commit c60f39ada625562bff26400f304690c19fe9f504, AKA gh-134686)

Co-authored-by: neonene <53406459+neonene@users.noreply.github.com>