Remove redundants "See" before @xref or @pxref (Bug#35793)

Remove redundants "See" before @xref or @pxref (Bug#35793)

* doc/lispref/control.texi (Control Structures):
* doc/lispref/modes.texi (Search-based Fontification):
* doc/misc/cc-mode.texi (Filling and Line Breaking Commands)
(Auto-newline Insertion, Other Special Indentations):
* doc/misc/dbus.texi (Errors and Events):
* doc/misc/dired-x.texi (Find File At Point):
* doc/misc/eudc.texi (Display of Query Results, Inline Query Expansion):
* doc/misc/gnus-faq.texi (FAQ 3-11):
* doc/misc/gnus.texi (Group Parameters, Posting Styles)
(Spam Package Introduction):
* doc/misc/org.texi (LaTeX fragments, Previewing LaTeX fragments):
* doc/misc/reftex.texi (Commands):
Remove redundant "See" before cross references.
* doc/lispref/functions.texi (Function Safety): Redundant "see" is in
ignored text, but remove it anyway.
* doc/lispref/positions.texi (Skipping Characters): Remove redundant
"See" before cross references.  Change @xref to @pxref, which is
more suitable when at the end of a sentence.

Most of the redundants "See" found by Noam Postavsky.