[nrf noup] tests: drivers: build_all: regulator: use old schema

New Twister schema is not supported yet in sdk-zephyr, drop this patch
once Twister is updated.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
(cherry picked from commit 104d43f)
(cherry picked from commit cf56646)

Author: gmarull

tests/drivers/build_all/regulator/testcase.yaml

@@ -3,9 +3,7 @@
 
 tests:
   drivers.regulator.build:
-    tags:
-      - drivers
-      - regulator
+    tags: drivers regulator
     build_only: true
     platform_allow:
       - native_posix