Remove Frient EMI Norwegian HAN divisor workaround

[TheJulianJES]

Proposed change

This removes the workaround for the Frient EMI Norwegian HAN, which previously blocked attribute reports for the divisor attribute, similar to Z2M here. With HA Core 2026.2.0 and later, this should no longer be needed.

The Frient EMI HAN test was also changed to use a message from a real device (with the mfr-specific bit set).

Additional information

This essentially reverts the following PR:

• Fix Frient EMI Norwegian HAN divisor #4396

There's more context in the comments of that PR. @uvNikita was able to grab such an attribute report for the manufacturer specific attribute that conflicts with the ZCL divisor attribute and we confirmed the is_manufacturer_specific bit is correctly set, meaning that zigpy no longer parses those attribute reports for the ZCL attribute. (Thanks!!)

• In a future PR, we can implement support for the Frient specific attributes.
• The "quirk" (temporarily without function) was kept, as we still have a test for this device and plan to add more functionality to it soon.
• We should only merge this for HA Core 2026.3.x.

Device diagnostics

See this comment: #4396 (comment)

Checklist

• The changes are tested and work correctly
• pre-commit checks pass / the code has been formatted using Black
• Tests have been added to verify that the new code works
• Device diagnostics data has been attached

[TheJulianJES]

This also removes the _CONSTANT_ATTRIBUTES workaround to set the divisor to a fixed 1000. We should make sure that when reading the attribute (with this modified empty quirk), the device actually returns 1000.

[TheJulianJES]

Hmm, looks like zigpy is still parsing the attribute report for the divisor, even though it has a manufacturer code set? Need to check this later.

[puddly]

We will still emit an attribute report event if an attribute definition doesn't exist, for backwards compatibility.

[TheJulianJES]

Ah, right. A bunch of things in zigpy/quirks still rely on the IDs anyway (ClusterListener, _CONSTANT_ATTRIBUTES). Those need to allow definition reference (or name) for this.

For reference, also left a comment about this here: zigpy/zigpy#1760 (comment)