* lisp/progmodes/sh-script.el: Remove old non-SMIE indentation code

(sh-learn-basic-offset, sh-blink, sh-use-smie): Remove config vars.
(sh-kw-alist, sh-learned-buffer-hook): Remove var.
(sh-must-support-indent, sh-mark-init, sh-mark-line): Remove function.
(sh-kw, sh-special-keywords): Remove constant.
(sh-help-string-for-variable, sh-read-variable, sh-goto-matching-if)
(sh-handle-prev-if, sh-handle-this-else, sh-handle-prev-else)
(sh-handle-this-fi, sh-handle-prev-fi, sh-handle-this-then)
(sh-handle-prev-then, sh-handle-prev-open, sh-handle-this-close)
(sh-goto-matching-case, sh-handle-prev-case, sh-handle-this-esac)
(sh-handle-prev-esac, sh-handle-after-case-label)
(sh-handle-prev-case-alt-end, sh-safe-forward-sexp)
(sh-goto-match-for-done, sh-handle-this-done, sh-handle-prev-done)
(sh-handle-this-do, sh-handle-prev-do, sh-find-prev-switch)
(sh-handle-this-rc-case, sh-handle-prev-rc-case, sh-check-rule)
(sh-get-indent-info, sh-get-indent-var-for-line, sh-prev-line)
(sh-prev-stmt, sh-get-word, sh-prev-thing, sh-this-is-a-continuation)
(sh-get-kw, sh-find-prev-matching, sh-set-var-value)
(sh-calculate-indent, sh-indent-line, sh-blink, sh-guess-basic-offset):
Remove functions.
(sh-show-indent, sh-set-indent, sh-learn-line-indent)
(sh-learn-buffer-indent): Redefine as obsolete aliases.

etc/NEWS

@@ -85,6 +85,9 @@ shows equivalent key bindings for all commands that have them.
 
 * Changes in Specialized Modes and Packages in Emacs 28.1
 
+---
+** The old non-SMIE indentation of 'sh-mode' has been removed.
+
 ---
 ** The sb-image.el library is now marked obsolete.
 This file was a compatibility kludge which is no longer needed.