Import TF-M OS wrapper dependencies to Mbed OS

Previous, we patched TF-M to replace its OS wrapper with CMSIS RTOS
to resolve manage management issue when integrated with Mbed OS. But
as of TF-M v1.2, the OS wrapper has been reworked in the vanilla TF-M,
and now it makes identical calls to its underlying CMSIS RTOS as our
patches do. So, we remove our patches and use vanilla TF-M's OS
wrapper instead to avoid extra maintenance overhead.

This commit
* updates `tfm_ns_import.yaml` to imports necessary OS wrapper
  dependencies into Mbed OS
* Remove `tfm/app/os_wrapper_cmsis_rtos_v2.c` inside this repository,
  as the file is now imported to Mbed OS which requires it

Author: LDong-Arm

tfm/app/os_wrapper_cmsis_rtos_v2.c

@@ -96,13 +96,21 @@
                 "src": "install/export/tfm/include",
                 "dst": "platform/FEATURE_EXPERIMENTAL_API/FEATURE_PSA/TARGET_TFM/TARGET_TFM_LATEST/include"
             },
+            {
+                "src": "../interface/include/os_wrapper",
+                "dst": "platform/FEATURE_EXPERIMENTAL_API/FEATURE_PSA/TARGET_TFM/TARGET_TFM_LATEST/include/os_wrapper"
+            },
             {
                 "src": "install/export/tfm/include/psa",
                 "dst": "platform/FEATURE_EXPERIMENTAL_API/FEATURE_PSA/TARGET_TFM/TARGET_TFM_LATEST/include/psa"
             },
             {
                 "src": "install/export/tfm/include/psa_manifest",
                 "dst": "platform/FEATURE_EXPERIMENTAL_API/FEATURE_PSA/TARGET_TFM/TARGET_TFM_LATEST/include/psa_manifest"
+            },
+            {
+                "src": "../../tf-m-tests/app/os_wrapper_cmsis_rtos_v2.c",
+                "dst": "platform/FEATURE_EXPERIMENTAL_API/FEATURE_PSA/TARGET_TFM/TARGET_TFM_LATEST/src/os_wrapper_cmsis_rtos_v2.c"
             }
         ],
         "v8-m": [