Remove 3 unnecessary sequences from our schema

In #361759 (comment 943916159) we determined there are 3 sequences in our database schema that are never used and don't make any sense to use as they always need to be set on INSERT so we should just remove them from our schema to avoid future confusion. They are:

1. ci_build_report_results_build_id_seq
2. ci_job_artifact_states_job_artifact_id_seq
3. ci_pipelines_config_pipeline_id_seq