boards: qemu_cortex_r5: Remove ignore tags for working tests

This commit removes the ignore tags for the tests that work after the
changes in the PR #20267.

In the future, this ignored testing tag list will be further reduced
as critical bugs for the qemu_cortex_r5 platform are addressed
(see #20217).

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

boards/arm/qemu_cortex_r5/qemu_cortex_r5.yaml

@@ -14,14 +14,7 @@ testing:
   ignore_tags:
     - benchmark
     - cmsis_rtos
-    - cpp
     - interrupt
-    - introduction
-    - logging
     - kernel
     - memory_protection
-    - posix
-    - sleep
-    - timer
     - userspace
-    - tracing