tests/net: Don't test on native_posix

native_posix is now deprecated.
Building these tests in both native_sim and native_posix does not
improve coverage for the tests or subsystem but doubles CI time.
As anyhow native_posix will be removed all together in
2 releases, let's remove it already for these.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

tests/net/ieee802154/6lo_fragment/testcase.yaml

@@ -1,8 +1,6 @@
 tests:
   net.ieee802154.fragment:
     platform_allow:
-      - native_posix
-      - native_posix/native/64
       - native_sim
       - native_sim/native/64
     integration_platforms:

tests/net/ieee802154/custom_l2/testcase.yaml

@@ -1,8 +1,6 @@
 tests:
   net.ieee802154.custom_l2:
     platform_allow:
-      - native_posix
-      - native_posix/native/64
       - native_sim
       - native_sim/native/64
     integration_platforms:

tests/net/ieee802154/l2/testcase.yaml

@@ -1,7 +1,5 @@
 common:
   platform_allow:
-    - native_posix
-    - native_posix/native/64
     - native_sim
     - native_sim/native/64
   integration_platforms:

tests/net/lib/coap_client/testcase.yaml

@@ -3,6 +3,5 @@ common:
 tests:
   net.coap.client:
     platform_allow:
-      - native_posix
       - native_sim
     tags: coap net

tests/net/ptp/clock/testcase.yaml

@@ -4,7 +4,6 @@ common:
   platform_allow:
     - frdm_k64f
     - sam_e70_xplained/same70q21
-    - native_posix
     - native_sim
   integration_platforms:
     - native_sim

tests/net/traffic_class/testcase.yaml

@@ -1,7 +1,5 @@
 common:
   platform_allow:
-    - native_posix
-    - native_posix/native/64
     - native_sim
     - native_sim/native/64
   integration_platforms: