Reverts the following commits:
- c81ec6f26d:
"Exposes capture methods to AudioServer, variable renames for
consistency, added documentation."
- 47c558b98a:
"Expose audio callbacks as signals."
- dabaa11b3c:
"Fix to make sure the capture buffers are deallocated at shutdown.
Silences warnings."
Some documentation improvements were kept for pre-existing methods.
See rationale for reverting these changes in #30468.
837adb30fd