Merge #19060 #19154

19060: SUBSYSTEMS.md: migrate subsystem list from wiki r=maribu a=jia200x



19154: tests/gcoap_dns: Remove duplicate r=miri64 a=Teufelchen1

### Contribution description

Removes a duplicated test. Originally, the test should have looked different and not be a duplicate. However, the behavior the test aimed at is no longer present anyway, hence it can be removed - rather than fixed. 

Further insights can be provided by `@miri64` 

Co-authored-by: Jose Alamos <jose@alamos.cc>
Co-authored-by: Teufelchen1 <bennet.blischke@haw-hamburg.de>

SUBSYSTEMS.md

@@ -0,0 +1,110 @@
+# RIOT Subsystem Maintainers
+
+This file gives an overview about the maintainers of RIOT subsystems. Whenever
+you submit an issue or a Pull Request, please assign one of the maintainers of
+the affected modules as an assignee in the issue tracker. The maintainer takes
+care of either fixing/merging the issue/PR herself or re-assign the issue to a
+qualified developer.
+
+**Note**: A developer might maintain more than one subsystem and an issue might
+affect more than one module.
+
+# CPU
+## ESP32, ESP8266
+
+## MSP430
+
+## ARM7
+
+## ARM Cortex-M
+
+## Atmel AVR (Atmega)
+
+## Native
+
+# Hardware modules
+
+## Network devices
+### IEEE 802.15.4
+
+### BLE
+
+### LoRa
+
+### CC110X
+
+### ESP-NOW
+
+## Peripherals
+
+## Other drivers
+
+# Kernel (core)
+
+# System libraries
+
+## High-level timer API (xtimer, ztimer)
+
+## Power Management
+
+## File Systems
+
+## USB support
+
+## POSIX support
+
+## Scripting languages
+
+## RUST support
+
+## C++ support
+
+## Crypto
+
+# Networking
+
+## Network stacks
+### GNRC
+
+### CCN-Lite
+
+### OpenThread
+
+### LWIP
+
+### OpenWSN
+
+## Physical/Link Layer
+### LoRaWAN
+
+### BLE (nimble)
+
+### IEEE 802.15.4
+
+## Interfaces
+### Sock
+
+### Netif
+
+### Netdev
+
+## 6LowPAN
+
+## Application protocols
+### CoAP
+
+### MQTT
+
+### LWM2M
+
+## Others
+
+### DTLS
+
+### RPL
+
+# Build System
+
+# Documentation
+
+# Testing/CI

tests/gcoap_dns/main.c

@@ -139,16 +139,6 @@ static void test_server_uri_set__not_coap(void)
     TEST_ASSERT(!gcoap_dns_server_uri_is_set());
 }
 
-static void test_server_uri_set__no_dns_var(void)
-{
-    static const char uri[] = "https://example.org/";
-
-    TEST_ASSERT(!gcoap_dns_server_uri_is_set());
-    INIT_TEST_PSK(TEST_TAG);
-    TEST_ASSERT_EQUAL_INT(-EINVAL, gcoap_dns_server_uri_set(uri));
-    TEST_ASSERT(!gcoap_dns_server_uri_is_set());
-}
-
 static void test_server_uri_get__buf_too_short(void)
 {
     static const char uri[] = "coap://example.org/";
@@ -223,7 +213,6 @@ static int _unittests(int argc, char **argv)
         new_TestFixture(test_server_uri_set__success_2),
         new_TestFixture(test_server_uri_set__uri_too_long),
         new_TestFixture(test_server_uri_set__not_coap),
-        new_TestFixture(test_server_uri_set__no_dns_var),
         new_TestFixture(test_server_uri_get__buf_too_short),
         new_TestFixture(test_cred_add__success),
         new_TestFixture(test_cred_add__no_mem),