instead of specifying the build "mode", and assuming that
the build directory is always located at "build/${mode}", specify
the build directory explicitly. this allows us to use
`create-relocatable-package.py` to package artifacts built
at build directory whose path does not comply to the
naming convention, for instance, we might want to build
scylla in `build/yet-another-super-feature/release`.
so, in this change, we trade `--mode` for an option named
`--build-dir` and update `configure.py` accordingly.
Refs #15241
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
8bd9645d1d