Remove temporary method for backfilling records `ci_build_needs`

This issue is to remove the code that was temporarily introduced for the backfilling of records in the following MR:

The following discussion from !163429 (merged) should be addressed:

• @lauraXD started a discussion: (+3 comments)

  @rkadam3 - I assume we will get rid of this and the validation once the backfill is completed. Could you please create a follow-up to remove this code once it's done and attach the issue as a TODO with the milestone here?