manifest: Update sdk-zephyr revision

Includes updates to test-spec.yml to reduce testing when sdk-zephyr
is updated.

Signed-off-by: Rubin Gerritsen <rubin.gerritsen@nordicsemi.no>

west.yml

@@ -59,7 +59,7 @@ manifest:
     # https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/guides/modules.html
     - name: zephyr
       repo-path: sdk-zephyr
-      revision: 2119df306f5c9104d479f96c4c8af00857094f83
+      revision: 78106c74f4ac7936ef78dcddb8c6e1e578fe41dd
       import:
         # In addition to the zephyr repository itself, NCS also
         # imports the contents of zephyr/west.yml at the above