MDEV-26966: Remove innodb_force_load_corrupted

MySQL 5.5 in commit 177d8b0
introduced a configuration parameter innodb_force_load_corrupted
whose purpose was to allow a corrupted table to be dropped.

Given that MDEV-11412 in MariaDB 10.5.4 aims to allow any metadata
for a missing or corrupted table to be dropped, and given that
MDEV-17567 and MDEV-25506 and related tasks made DDL operations
crash-safe, the parameter no longer serves any purpose.

Because this obscure parameter was read-only (not settable by a client),
it seems that we can simply declare it with MARIADB_REMOVED_OPTION
(commit 1bc9cce) without breaking
any upgrades.

DICT_ERR_IGNORE_INDEX: Replaces DICT_ERR_IGNORE_INDEX_ROOT and
DICT_ERR_IGNORE_CORRUPT, which were always set equally.

dict_load_indexes(): Report "No indexes found for table" in
a uniform way, and only when the DICT_ERR_IGNORE_INDEX flag is
not set.

If the clustered index is marked corrupted, and the operation
is DICT_ERR_IGNORE_DROP (we are about to drop the table), we will
load the metadata; else, we will return DB_INDEX_CORRUPT.

If SYS_INDEXES.PAGE is FIL_NULL, report an error or warning
unless we are about to drop the table.

dict_load_table_one(): Simplify the logic.

Author: dr-m

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

@@ -765,18 +765,6 @@ NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	OFF,ON
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	NONE
-VARIABLE_NAME	INNODB_FORCE_LOAD_CORRUPTED
-SESSION_VALUE	NULL
-DEFAULT_VALUE	OFF
-VARIABLE_SCOPE	GLOBAL
-VARIABLE_TYPE	BOOLEAN
-VARIABLE_COMMENT	Force InnoDB to load metadata of corrupted table.
-NUMERIC_MIN_VALUE	NULL
-NUMERIC_MAX_VALUE	NULL
-NUMERIC_BLOCK_SIZE	NULL
-ENUM_VALUE_LIST	OFF,ON
-READ_ONLY	YES
-COMMAND_LINE_ARGUMENT	NONE
 VARIABLE_NAME	INNODB_FORCE_PRIMARY_KEY
 SESSION_VALUE	NULL
 DEFAULT_VALUE	OFF

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

@@ -5105,6 +5105,9 @@ static int init_server_components()
       MYSQL_COMPATIBILITY_OPTION("new"),
       MYSQL_COMPATIBILITY_OPTION("show_compatibility_56"),
 
+      /* The following options were removed in 10.6 */
+      MARIADB_REMOVED_OPTION("innodb-force-load-corrupted"),
+
       /* The following options were removed in 10.5 */
 #if defined(__linux__)
       MARIADB_REMOVED_OPTION("super-large-pages"),

mysql-test/suite/sys_vars/t/innodb_force_load_corrupted_basic.test

@@ -80,6 +80,7 @@ static const char *removed_variables[] =
 "innodb_file_format_check",
 "innodb_file_format_max",
 "innodb_flush_neighbor_pages",
+"innodb_force_load_corrupted",
 "innodb_foreground_preflush",
 "innodb_ibuf_accel_rate",
 "innodb_ibuf_active_contract",