Remove deprecated SYMLVL constants from characterProcessing (#13248)

Removes code deprecated as part of PR #11856

Summary of the issue:
PR #11856 converted module level constants for symbol levels in characterProcessing into an enum. The constants were marked for removal in 2022.1.

Description of how this pull request fixes the issue:
These constants are removed.

Testing strategy:
With git grep made sure that the removed symbol levels are not used in the source code.

source/characterProcessing.py

@@ -4,7 +4,6 @@
 # This file is covered by the GNU General Public License.
 # See the file COPYING for more details.
 
-from versionInfo import version_year
 from enum import IntEnum
 import os
 import codecs
@@ -136,15 +135,6 @@ class SymbolLevel(IntEnum):
 	UNCHANGED = -1
 
 
-# The following SYMLVL_ constants are deprecated in #11856 but remain to maintain backwards compatibility.
-# Remove these in 2022.1 and replace instances using them with the SymbolLevel IntEnum.
-if version_year < 2022:
-	SYMLVL_NONE = SymbolLevel.NONE
-	SYMLVL_SOME = SymbolLevel.SOME
-	SYMLVL_MOST = SymbolLevel.MOST
-	SYMLVL_ALL = SymbolLevel.ALL
-	SYMLVL_CHAR = SymbolLevel.CHAR
-
 SPEECH_SYMBOL_LEVEL_LABELS = {
 	# Translators: The level at which the given symbol will be spoken.
 	SymbolLevel.NONE: pgettext("symbolLevel", "none"),

user_docs/en/changes.t2t

@@ -95,6 +95,7 @@ This ensures code will honor the Windows user setting for swapping the primary m
 - ``winVersion.WIN10_RELEASE_NAME_TO_BUILDS`` is removed. (#13211)
 - SCons now builds with multiple concurrent jobs, equal to the number of logical processors in the system.
 This can dramatically decrease build times on multi core systems. (#13226)
+- ``characterProcessing.SYMLVL_*`` constants are removed - please use ``characterProcessing.SymbolLevel.*`` instead. (#13248)
 -