test: Add more delay for bootc to settle and avoid flaky

Signed-off-by: Xiaofeng Wang <henrywangxf@me.com>

Author: henrywang

tmt/tests/booted/bootc_testlib.nu

@@ -4,11 +4,8 @@
 # that seems to have appeared in C10S
 # TODO diagnose and fill in here
 export def reboot [] {
-    # Sometimes systemd daemons are still running old binaries and response "Access denied" when send reboot request
-    # Force a full sync before reboot
-    sync
     # Allow more delay for bootc to settle
-    sleep 30sec
+    sleep 120sec
 
     tmt-reboot
 }