Merge #17567: gui: remove macOS start on login code

27d82b63fb gui: remove macOS start on login code (fanquake)

Pull request description:

  The macOS startup item code was disabled for builds targeting macOS >
  `10.11` in #15208. Now that we require macOS `10.12` as a minimum (#17550),
  we can remove the startup item code entirely. The API we were using, `LSSharedFileListItemCopyResolvedURL`, `LSSharedFileListCopySnapshot` etc,
  was removed in macOS `10.12` SDK.

ACKs for top commit:
  jonasschnelli:
    utACK 27d82b63fb
  jonasschnelli:
    Tested ACK 27d82b63fb - successfully compiled on 10.15.1

Tree-SHA512: 7420757b91c7820e6a63280887155394547134a9cebcf3721af0284da23292627f94cd431241e033075b3fd86d79ace3ebf1b25d17763acbf71e07a742395409

doc/release-notes.md

@@ -90,6 +90,8 @@ Low-level Changes section below.
 GUI changes
 -----------
 
+- The "Start Bitcoin Core on system login" option has been removed on macOS.
+
 Wallet
 ------