[dv/aon_timer] rever temp fix regression error

Reverts #6823

Per Tom's comment on issue #6821, we are going to revert this temp fix and see if we can reproduce the assertion error.

Signed-off-by: Cindy Chen <chencindy@opentitan.org>
diff --git a/hw/ip/aon_timer/dv/env/seq_lib/aon_timer_base_vseq.sv b/hw/ip/aon_timer/dv/env/seq_lib/aon_timer_base_vseq.sv
index 525515f..0d71bf8 100644
--- a/hw/ip/aon_timer/dv/env/seq_lib/aon_timer_base_vseq.sv
+++ b/hw/ip/aon_timer/dv/env/seq_lib/aon_timer_base_vseq.sv
@@ -11,7 +11,7 @@
   `uvm_object_utils(aon_timer_base_vseq)
 
   // various knobs to enable certain routines
-  bit do_aon_timer_init = 1'b1;
+  rand bit do_aon_timer_init;
 
   // If this is set, the AON clock starts first and then the fast clock starts sometime later. If
   // not, they start in parallel. Since the fast clock is *much* quicker, the practical result is