Fix electra sanity testgen for blocks (#3939)

Author: jtraglia

tests/core/pyspec/eth2spec/test/electra/sanity/blocks/__init__.py

@@ -1 +1,4 @@
+# This is a "hack" which allows other test files (e.g., test_deposit_transition.py)
+# to reuse the sanity/block test format.
+from .test_blocks import *  # noqa: F401 F403
 from .test_deposit_transition import *  # noqa: F401 F403

tests/generators/sanity/main.py

@@ -28,6 +28,9 @@
     ]}
     deneb_mods = combine_mods(_new_deneb_mods, capella_mods)
 
+    # This is a "hack" which allows other test files (e.g., test_deposit_transition.py)
+    # to reuse the sanity/block test format. If a new test file is added or removed,
+    # do not forget to update sanity/block/__init__.py accordingly.
     _new_electra_mods = {key: 'eth2spec.test.electra.sanity.' + key for key in [
         'blocks',
     ]}