The definition of the template is in a source translation unit, but there
are also uses outside the translation unit. Without lto/pgo it worked due
to the definition in the translation unit, but with lto/pgo we can presume
the definition was inlined, so callers outside the translation unit did not
have anything to link with.
Fix by explicitly instantiating the template function.
Closesscylladb/scylladb#22136
de8253b98a