Revert "ZJIT: Resurrect --seed to stabilize CI"

This reverts commit 9d0b621.

It didn't work for `make check`. I'll fix it in a PR.

Author: k0kubun

.github/workflows/zjit-macos.yml

@@ -35,7 +35,6 @@ jobs:
           - test_task: 'check'
             configure: '--enable-zjit=dev'
             run_opts: '--zjit-call-threshold=1'
-            testopts: '--seed=11831'
             specopts: '-T --zjit-call-threshold=1'
 
           - test_task: 'zjit-check' # zjit-test + quick feedback of test_zjit.rb

.github/workflows/zjit-ubuntu.yml

@@ -54,7 +54,6 @@ jobs:
           - test_task: 'check'
             configure: '--enable-zjit=dev'
             run_opts: '--zjit-call-threshold=1'
-            testopts: '--seed=18140'
             specopts: '-T --zjit-call-threshold=1'
 
           - test_task: 'zjit-check' # zjit-test + quick feedback of test_zjit.rb