Merge bitcoin/bitcoin#23585: scripted-diff: Drop Darwin version for better maintainability

2f356a0ca8 scripted-diff: Drop Darwin version for better maintainability (Hennadii Stepanov)

Pull request description:

  After this PR, any macOS tools version bumping in the future will touch fewer files in the repo.

  Pointing a Darwin version for the `--host` system does not matter for the following reasons:

  - in terms of the resulted binaries, we should only care about the minimum supported macOS version which is a separated parameter in our build system.

  - in terms of the build system itself, the usage of the `$(host)` variable is self-consistent enough. Btw `$(host_os)` value already has the version dropped:
  ```
  $ make -C depends --no-print-directory print-host_os HOST=x86_64-apple-darwin19
  host_os=darwin
  ```

ACKs for top commit:
  gruve-p:
    ACK 2f356a0ca8
  promag:
    ACK 2f356a0ca8.
  fanquake:
    ACK 2f356a0ca8

Tree-SHA512: 374896ab0ba02b0d8b4b21431fe963bd213b0d09586e0898c13a4c5fa294c1b693f1b2c92880c245c4157c14217b4825b36522f461930477f4d2a727086ebb2a

ci/test/00_setup_env_mac.sh

@@ -8,7 +8,7 @@ export LC_ALL=C.UTF-8
 
 export CONTAINER_NAME=ci_macos_cross
 export DOCKER_NAME_TAG=ubuntu:20.04  # Check that Focal can cross-compile to macos
-export HOST=x86_64-apple-darwin19
+export HOST=x86_64-apple-darwin
 export PACKAGES="cmake imagemagick librsvg2-bin libz-dev libtiff-tools libtinfo5 python3-setuptools xorriso"
 export XCODE_VERSION=12.1
 export XCODE_BUILD_ID=12A7403

ci/test/00_setup_env_mac_host.sh

@@ -6,7 +6,7 @@
 
 export LC_ALL=C.UTF-8
 
-export HOST=x86_64-apple-darwin19
+export HOST=x86_64-apple-darwin
 export PIP_PACKAGES="zmq lief"
 export GOAL="install"
 export BITCOIN_CONFIG="--with-gui --enable-reduce-exports"