Exclude development gems from CI builds

We don't need these for tests, and excluding better_errors and
binding_of_caller from the list might get rid of the mysterious seg
faults.

rblineprof is used by `spec/lib/gitlab/sherlock/line_profiler_spec.rb`,
so we need to keep it for testing.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/11951