Remedy wrong-looking \(:?...\) regexp constructs

Remedy wrong-looking \(:?...\) regexp constructs

When we see \(:?...\) in a regexp it very much looks like a typo
for a \(?:...\) construct and often is, so do something about
all of these (one of which being another mistake).
Doing so silences an optional relint check.

* lisp/comint.el (comint-replace-by-expanded-history-before-point):
* lisp/term.el (term-replace-by-expanded-history-before-point):
Move :? out from capturing group where it does not need to be,
to avoid confusion.
* lisp/emacs-lisp/cl-indent.el (common-lisp-loop-part-indentation):
A capturing group isn't needed here; turn it into simple bracketing.
* lisp/progmodes/sql.el (sql--completion-table):
Change :? into ?: which was clearly meant here.