Matter: fix stale host test fixtures (#25161)

run_tests.be and button_stability_tests.be stop with assert_failed right
after "Matter epoch conversion for UTC and local time: OK" on development.
Three test-only mistakes, each hiding the next:

- run_tests.be checked the RSSI item's stored TLV type before encoding.
  "Clamp RSSI" (#25126) stores signed values as I4; the encoded bytes are
  still the 1-byte 00C3, which the next assert checks. Check the value only.
- TestGarageDevice (run_tests.be) lacks disable_bridge_mode, which
  Matter_Plugin_Device.init() reads since #25099.
- StabilityDevice (button_stability_tests.be) lacks it too.

Tests only; no firmware files change.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

lib/libesp32/berry_matter/tests/button_stability_tests.be

@@ -74,9 +74,10 @@ def test_button_stability()
     def init() self.im = TestInteractionModel() end
   end
   class StabilityDevice
-    var events, message_handler, updates
+    var events, message_handler, updates, disable_bridge_mode
     def init()
       self.updates = 0
+      self.disable_bridge_mode = false
       self.message_handler = TestMessageHandler()
       self.events = MemoryEventHandler(self)
     end

lib/libesp32/berry_matter/tests/run_tests.be

@@ -206,9 +206,10 @@ class TestGarageEvents
 end
 
 class TestGarageDevice
-  var tick, events
+  var tick, events, disable_bridge_mode
   def init()
     self.tick = 1
+    self.disable_bridge_mode = false
     self.events = TestGarageEvents()
   end
   def attribute_updated(endpoint, cluster, attribute, fabric_specific) end
@@ -349,7 +350,7 @@ ctx.attribute = 0x0003
 assert(root.read_attribute(session, ctx, TLV.Matter_TLV_item()).val == 6)
 ctx.attribute = 0x0004
 var rssi = root.read_attribute(session, ctx, TLV.Matter_TLV_item())
-assert(rssi.typ == 0x00 && rssi.val == -61)
+assert(rssi.val == -61)            # stored as I4 by convention; next line checks the encoded I1
 assert(rssi.tlv2raw() == bytes("00C3"))
 tasmota.wifi_info['security'] = 'wpa3-enterprise'      # unknown mode maps to Unspecified
 tasmota.wifi_info['phy'] = ''                          # unknown PHY is null