optimized_clang.sh trains the compiler using profile-guided optimization
(pgo). However, while doing that, it builds scylladb using its own profile
stored in pgo/profiles and decompressed into build/profile.profdata. Due
to the funky directory structure used for training the compiler, that
path is invalid during the training and the build fails.
The workaround was to build on a cloud machine instead of a workstation -
this worked because the cloud machine didn't have git-lfs installed, and
therefore did not see the stored profile, and the whole mess was averted.
To make this work on a machine that does have access to stored profiles,
disable use of the stored profile even if it exists.
Fixes#22713Closesscylladb/scylladb#24571
(cherry picked from commit 52f11e140f)
Closesscylladb/scylladb#24620
477cad246f