org-indent-line: Do not rely upon TAB being bound to indentation

* lisp/org.el (org-indent-line): When indenting natively in src
blocks, call `indent-line-function' instead of relying upon "TAB"
binding doing indentation.

lisp/org.el

@@ -19660,7 +19660,7 @@ Also align node properties according to `org-property-format'."
                       (org-with-point-at (org-element-property :begin element)
                         (+ (org-current-text-indentation)
                            org-edit-src-content-indentation)))))
-               (org-babel-do-key-sequence-in-edit-buffer (kbd "TAB"))
+               (org-babel-do-in-edit-buffer (funcall indent-line-function))
                (when (and block-content-ind (looking-at-p "^$"))
                  (indent-line-to block-content-ind))))
 	    (t