chassis: Remove deprecated IntrusionSensorNumber

The DMTF Chassis schema deprecated `IntrusionSensorNumber` at v1.22.0
with the rationale: "This property has been deprecated in order to allow
for multiple physical sensors to construct this object."

The field was hardcoded to `1` inside the D-Bus callback for
`PhysicalSecurity` and was never populated from D-Bus, so it carried no
real data. Keeping it in the response actively misleads clients that
rely on it to identify a unique sensor.

Remove the two-line assignment so the Chassis GET response no longer
emits `PhysicalSecurity/IntrusionSensorNumber`. No in-tree consumers of
this property were found.

BREAKING CHANGE: `PhysicalSecurity/IntrusionSensorNumber` is no longer
present in the Chassis GET response.

This property was introduced in commit c181942f ("redfish: chassis: add
property of physical security").

Tested:
Verified GET /redfish/v1/Chassis/{ChassisId} response no
longer contains the `PhysicalSecurity/IntrusionSensorNumber`
field.

Change-Id: I6ddff9588ba7839056bf45174a11eaeeffcb86b4
Signed-off-by: Joel Pullokaran Jesin <joelpj@ami.com>