MDEV-15995 Drop extra semicolon in VARIABLE_COMMENT for SYSTEM_VERSIONING_ALTER_HISTORY

mysql-test/main/mysqld--help.result

@@ -1238,7 +1238,7 @@ The following specify which files/extra groups are read (specified before remain
  --system-versioning-alter-history=name 
  Versioning ALTER TABLE mode. ERROR: Fail ALTER with
  error; KEEP: Keep historical system rows and subject them
- to ALTER; 
+ to ALTER
  --table-cache=#     Deprecated; use --table-open-cache instead.
  --table-definition-cache=# 
  The number of cached table definitions

mysql-test/suite/sys_vars/r/sysvars_server_embedded.result

@@ -4093,7 +4093,7 @@ GLOBAL_VALUE_ORIGIN	COMPILE-TIME
 DEFAULT_VALUE	ERROR
 VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	ENUM
-VARIABLE_COMMENT	Versioning ALTER TABLE mode. ERROR: Fail ALTER with error; KEEP: Keep historical system rows and subject them to ALTER; 
+VARIABLE_COMMENT	Versioning ALTER TABLE mode. ERROR: Fail ALTER with error; KEEP: Keep historical system rows and subject them to ALTER
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -5045,7 +5045,7 @@ GLOBAL_VALUE_ORIGIN	COMPILE-TIME
 DEFAULT_VALUE	ERROR
 VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	ENUM
-VARIABLE_COMMENT	Versioning ALTER TABLE mode. ERROR: Fail ALTER with error; KEEP: Keep historical system rows and subject them to ALTER; 
+VARIABLE_COMMENT	Versioning ALTER TABLE mode. ERROR: Fail ALTER with error; KEEP: Keep historical system rows and subject them to ALTER
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL

sql/sys_vars.cc

@@ -400,7 +400,7 @@ static const char *vers_alter_history_keywords[]= {"ERROR", "KEEP", NullS};
 static Sys_var_enum Sys_vers_alter_history(
        "system_versioning_alter_history", "Versioning ALTER TABLE mode. "
        "ERROR: Fail ALTER with error; " /* TODO: fail only when history non-empty */
-       "KEEP: Keep historical system rows and subject them to ALTER; ",
+       "KEEP: Keep historical system rows and subject them to ALTER",
        SESSION_VAR(vers_alter_history), CMD_LINE(REQUIRED_ARG),
        vers_alter_history_keywords, DEFAULT(VERS_ALTER_HISTORY_ERROR));