Simplify initialization of CILJit singleton

[jkotas]

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Issue Details

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Author:	jkotas
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[jakobbotsch]

LGTM provided CI is green

[jkotas]

System.Net.WebSockets.Client.Tests crashed on Libraries Test Run checked coreclr Linux_musl x64 Debug. Stacktrace:

Call Site
libcoreclr!Object::GetGCSafeMethodTable [/__w/1/s/src/coreclr/vm/object.h @ 446] 
libcoreclr!Object::ValidateInner+0x1b0
libcoreclr!Object::Validate+0x8a [/__w/1/s/src/coreclr/vm/object.cpp @ 1124] 
libcoreclr!OBJECTREF::OBJECTREF+0xfa [/__w/1/s/src/coreclr/vm/object.cpp @ 1124] 
libcoreclr!ObjectFromHandle+0x2c [/__w/1/s/src/coreclr/vm/gchandleutilities.h @ 44] 
libcoreclr!MarshalNative::GCHandleInternalGet+0x50

Tracked by #69125