.editorconfig: unify free-standing bash indent with Nix-embedded bash indent (#388089)

.editorconfig

@@ -35,8 +35,12 @@ indent_size = 1
 [*.{json,lock,md,nix,rb}]
 indent_size = 2
 
-# Match perl/python/shell scripts, set indent width of four
-[*.{bash,pl,pm,py,sh}]
+# Match all the Bash code in Nix files, set indent width of two
+[*.{bash,sh}]
+indent_size = 2
+
+# Match Perl and Python scripts, set indent width of four
+[*.{pl,pm,py}]
 indent_size = 4
 
 # Match gemfiles, set indent to spaces with width of two