Remove "utc" type. (#23985)

It's deprecated in the spec, and is just an alias for epoch_s.  And we
were not handling it correctly in our code, so using it would break
things.

Fixes #23982

src/app/tests/suites/certification/Test_TC_TSTAT_2_1.yaml

@@ -541,7 +541,7 @@ tests:
       attribute: "SetpointChangeSourceTimestamp"
       response:
           constraints:
-              type: utc
+              type: epoch_s
 
     - label: "Read OccupiedSetback attribute from the DUT"
       PICS: TSTAT.S.F02

src/app/zap-templates/zcl/data-model/chip/chip-types.xml

@@ -53,7 +53,6 @@ limitations under the License.
     <type id="0x44" description="Long Character String"    name="long_char_string"            composite="true"/>
     <type id="0xE0" description="Time of day"              name="tod"               size="4"  analog="true"   />
     <type id="0xE1" description="Date"                     name="date"              size="4"  analog="true"   />
-    <type id="0xE2" description="UTC Time"                 name="utc"               size="4"  analog="true"   />
     <type id="0xE3" description="Epoch Microseconds"       name="epoch_us"          size="8"  analog="true"   />
     <type id="0xE4" description="Epoch Seconds"            name="epoch_s"           size="4"  analog="true"   />
     <type id="0xE5" description="System Time Microseconds" name="systime_us"        size="8"  analog="true"   />

src/app/zap-templates/zcl/data-model/chip/thermostat-cluster.xml

@@ -111,7 +111,7 @@ limitations under the License.
     <attribute side="server" code="0x0029" define="THERMOSTAT_RUNNING_STATE" type="BITMAP16" writable="false" optional="true">ThermostatRunningState</attribute>
     <attribute side="server" code="0x0030" define="SETPOINT_CHANGE_SOURCE" type="ENUM8" writable="false" optional="true">SetpointChangeSource</attribute>
     <attribute side="server" code="0x0031" define="SETPOINT_CHANGE_AMOUNT" type="INT16S" writable="false" default="0x8000" optional="true" isNullable="true">SetpointChangeAmount</attribute>
-    <attribute side="server" code="0x0032" define="SETPOINT_CHANGE_SOURCE_TIMESTAMP" type="utc" writable="false" optional="true">SetpointChangeSourceTimestamp</attribute>
+    <attribute side="server" code="0x0032" define="SETPOINT_CHANGE_SOURCE_TIMESTAMP" type="epoch_s" writable="false" optional="true">SetpointChangeSourceTimestamp</attribute>
     <attribute side="server" code="0x0034" define="OCCUPIED_SETBACK" type="int8u" writable="true" optional="true" isNullable="true">
       <description>OccupiedSetback</description>
       <access op="read" privilege="view"/>