[adc] Collapse duplicate CI test variants (#20400)

tests/components/adc/test.nrf52-mcumgr.yaml

@@ -1,23 +0,0 @@
-sensor:
-  - platform: adc
-    pin: VDDHDIV5
-    name: "VDDH Voltage"
-    update_interval: 5sec
-    filters:
-      - multiply: 5
-  - platform: adc
-    pin: VDD
-    name: "VDD Voltage"
-    update_interval: 5sec
-  - platform: adc
-    pin: AIN0
-    name: "AIN0 Voltage"
-    update_interval: 5sec
-  - platform: adc
-    pin: P0.03
-    name: "AIN1 Voltage"
-    update_interval: 5sec
-  - platform: adc
-    name: "AIN2 Voltage"
-    update_interval: 5sec
-    pin: 4

tests/components/adc/validate.bk72xx-ard.yaml

@@ -1,3 +1,5 @@
+# Config only: every LibreTiny chip compiles the same ADC code, covered by the
+# ln882x-ard build; this checks the BK72xx analog pin names.
 sensor:
   - id: adc_my_sensor
     platform: adc

tests/components/adc/validate.esp32-p4-idf.yaml

@@ -1,3 +1,5 @@
+# Config only: the P4 compiles the same ADC code as the esp32-s3-idf build
+# (curve fitting calibration), only the pin table differs.
 sensor:
   - id: adc_my_sensor
     platform: adc

tests/components/adc/validate.esp32-s2-idf.yaml

@@ -1,3 +1,6 @@
+# Config only: the S2 shares the C2's line fitting path (no default_vref) and
+# the original ESP32's ADC init (no clk_src); both are compiled by those
+# builds, only the S2 pin table differs.
 sensor:
   - id: adc_my_sensor
     platform: adc