Truncate `ci_pipelines_config` and `ci_build_trace_metadata`

Problem

We need to look for low hanging fruit opportunities to remove CI data that is unecessary to save on disk space.

Proposal

From !128966 (comment 1935372341) - @mbobin:

I think there are other space saving opportunities, like truncating ci_pipelines_config and ci_build_trace_metadata since they store internal data and reintroduce them as partitioned. This should free up around 800GB: https://console.postgres.ai/gitlab/ci_production/reports/3139/files/514773/md

Follow the steps 2 through 7 to partition the table in the same MR as the one that truncates the table: https://docs.gitlab.com/ee/development/database/partitioning/list.html#