Fix PostgreSQL cleanup query that never deletes orphan mesh rows (Ylianst#7798)

The cleanup pass on PostgreSQL is supposed to garbage-collect rows whose
`extra` references a mesh ID that no longer exists in the current `meshlist`
(matching the MongoDB branch a few lines down). As written:

    DELETE FROM Main WHERE ((extra != NULL)
                       AND (extra LIKE ('mesh/%'))
                       AND (extra != ANY ($1)))

Two interlocking bugs:

1. `extra != NULL` is invalid SQL. In three-valued logic, `<expr> != NULL`
   evaluates to NULL, which the WHERE clause treats as falsy. The AND chain
   is therefore always NULL/falsy and zero rows are ever deleted. PostgreSQL's
   `transform_null_equals` setting only affects `=`, not `<>`/`!=`, and is
   off by default. Result today: cleanup silently no-ops on Postgres and
   orphan mesh-extra rows accumulate forever.

2. `<> ANY (array)` is *not* "not in the list" semantics. It returns TRUE
   when at least one array element is not equal to the value -- which is
   true for almost every input as soon as `meshlist` has 2+ distinct
   elements. Naively fixing only bug #1 (e.g., to `extra IS NOT NULL`)
   would mass-delete every row matching `extra LIKE 'mesh/%'`, including
   rows whose mesh is in the current list. The correct form is
   `<> ALL (array)`.

This patch replaces both with the minimal correct query:

    DELETE FROM main WHERE extra LIKE 'mesh/%' AND extra <> ALL ($1)

The redundant `extra != NULL` predicate is dropped because `extra LIKE
'mesh/%'` already filters out NULLs. The `<> ALL` form matches the intent
of the parallel MongoDB query (`{ meshid: { $exists: true, $nin: meshlist } }`).

`Main` -> `main` is cosmetic (PostgreSQL folds unquoted identifiers to
lowercase), included only to match the actual `CREATE TABLE main` schema
at db.js:1407 and other queries throughout the file.

Note: the MariaDB/MySQL branch on the next line is also broken (mismatched
parens; query throws on every call). That is a separate fix.

Author: adamdewolf

db.js

@@ -454,7 +454,7 @@ module.exports.CreateDB = function (parent, func) {
 
                         } else if (obj.databaseType == DB_POSTGRESQL) {
                             // Postgres
-                            sqlDbQuery('DELETE FROM Main WHERE ((extra != NULL) AND (extra LIKE (\'mesh/%\')) AND (extra != ANY ($1)))', [meshlist], function (err, response) { });
+                            sqlDbQuery('DELETE FROM main WHERE extra LIKE \'mesh/%\' AND extra <> ALL ($1)', [meshlist], function (err, response) { });
                         } else if ((obj.databaseType == DB_MARIADB) || (obj.databaseType == DB_MYSQL)) {
                             // MariaDB
                             sqlDbQuery('DELETE FROM Main WHERE (extra LIKE ("mesh/%") AND (extra NOT IN ?)', [meshlist], function (err, response) { });