Sensors remove reliance on global variable (#16344)

* Sensors remove reliance on global variable

* Apply fixes from StyleCI

* Clear the instance instead of reset.
Remove $valid['sensors'] from docs

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Co-authored-by: Tony Murray <murrant@users.noreply.github.com>

includes/discovery/sensors/dbm/awplus.inc.php

@@ -15,7 +15,7 @@ if ($pre_cache['awplus-sfpddm']) {
             $descr = $tmp['ifName'];
             $oid = '.1.3.6.1.4.1.207.8.4.4.3.28.1.4.1.3.' . $index;
             discover_sensor(
-                $valid['sensor'],
+                null,
                 'dbm',
                 $device,
                 $oid,
@@ -51,7 +51,7 @@ if ($pre_cache['awplus-sfpddm']) {
             $descr = $tmp['ifName'];
             $oid = '.1.3.6.1.4.1.207.8.4.4.3.28.1.5.1.3.' . $index;
             discover_sensor(
-                $valid['sensor'],
+                null,
                 'dbm',
                 $device,
                 $oid,