Merge bitcoindevkit#2190: Remove unused start-core.sh script

ae0e826 chore: remove unused `start-core.sh` script (Luis Schwab)

Pull request description:

  ## Changelog
  ```
  - Remove the unused `ci/start-core.sh` script
  ```

ACKs for top commit:
  oleonardolima:
    ACK ae0e826
  evanlinjin:
    ACK ae0e826

Tree-SHA512: af9205cfb0de497f16fa10d49afd2f87291f79e19157a784b7e97ec8cf75bdffc1c4c5a71f755f0c16074b2afa96560001951551554749ff5ae57e3898202908

Author: evanlinjin