Further make sure graphviz is truly optional feature on MacOS

For our development, Pygraphviz is quite a difficul dependency to
install on MacOS. That's why we disable it by default on MacOS -
it was attempted in #43604, but it turned out some other dependencies
pulled it in as well.

This PR removes all the graphviz dependencies as being required,
and providers more readable error message and iink to documuentation
explaining how to install graphviz if needed.

hatch_build.py

@@ -180,8 +180,11 @@
     ],
     "doc-gen": [
         "apache-airflow[doc]",
-        "diagrams>=0.23.4",
-        "eralchemy2>=1.3.8",
+        # The graphviz package creates friction when installing on MacOS as it needs graphviz system package to
+        # be installed, and it's really only used for very obscure features of Airflow, so we can skip it on MacOS
+        # Instead, if someone attempts to use it on MacOS, they will get explanatory error on how to install it
+        "diagrams>=0.23.4; sys_platform != 'darwin'",
+        "eralchemy2>=1.3.8; sys_platform != 'darwin'",
     ],
     # END OF doc extras
 }

scripts/ci/pre_commit/generate_airflow_diagrams.py

@@ -44,9 +44,19 @@ def main():
         hash_file = source_file.with_suffix(".md5sum")
         if not hash_file.exists() or not hash_file.read_text().strip() == str(checksum).strip():
             console.print(f"[bright_blue]Changes in {source_file}. Regenerating the image.")
-            subprocess.run(
-                [sys.executable, source_file.resolve().as_posix()], check=True, cwd=source_file.parent
+            process = subprocess.run(
+                [sys.executable, source_file.resolve().as_posix()], check=False, cwd=source_file.parent
             )
+            if process.returncode != 0:
+                if sys.platform == "darwin":
+                    console.print(
+                        "[red]Likely you have no graphviz installed[/]"
+                        "Please install eralchemy2 package to run this script. "
+                        "This will require to install graphviz, "
+                        "and installing graphviz might be difficult for MacOS. Please follow: "
+                        "https://pygraphviz.github.io/documentation/stable/install.html#macos ."
+                    )
+                sys.exit(1)
             hash_file.write_text(str(checksum) + "\n")
         else:
             console.print(f"[bright_blue]No changes in {source_file}. Not regenerating the image.")

scripts/in_container/run_prepare_er_diagram.py

@@ -23,6 +23,7 @@
 from __future__ import annotations
 
 import os
+import sys
 from pathlib import Path
 
 from checksumdir import dirhash
@@ -34,9 +35,19 @@
 
 MIGRATIONS_DIR = AIRFLOW_SOURCES_ROOT / "airflow" / "migrations"
 if __name__ == "__main__":
-    from eralchemy2 import render_er
-
     console = Console(width=400, color_system="standard")
+    try:
+        from eralchemy2 import render_er
+    except ImportError:
+        if sys.platform == "darwin":
+            console.print(
+                "[red]Likely you have no graphviz installed[/]"
+                "Please install eralchemy2 package to run this script. "
+                "This will require to install graphviz, "
+                "and installing graphviz might be difficult for MacOS. Please follow: "
+                "https://pygraphviz.github.io/documentation/stable/install.html#macos ."
+            )
+        exit(1)
 
     console.print("[bright_blue]Preparing diagram for Airflow ERD")
     sha256hash = dirhash(