fix: pubsub worker stuck in jruby

[supercaracal]

In jRuby environment, even though our test cases was printed success log at finished, the parent process was waiting some children until the job was timed out in the workflow, then the CI was failure. the child was waiting for:

$ jstack -l PID

"Ruby-0-Thread-110: /home/kasuga/vcs/redis-cluster-client/lib/redis_client/cluster/pub_sub.rb:37" #200 [297874] daemon prio=5 os_prio=0 cpu=2951.28ms elapsed=146.67s tid=0x000076070863b5a0 nid=297874 runnable  [0x00007605305fe000]
   java.lang.Thread.State: TIMED_WAITING (parking)
        at jdk.internal.misc.Unsafe.park(java.base@23/Native Method)
        - parking to wait for  <0x000000070c173b88> (a java.util.concurrent.Semaphore$NonfairSync)
        at java.util.concurrent.locks.LockSupport.parkNanos(java.base@23/LockSupport.java:269)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(java.base@23/AbstractQueuedSynchronizer.java:756)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(java.base@23/AbstractQueuedSynchronizer.java:1126)
        at java.util.concurrent.Semaphore.tryAcquire(java.base@23/Semaphore.java:415)
        at org.jruby.RubyThread$SleepTask2.run(org.jruby.dist/RubyThread.java:1735)
        at org.jruby.RubyThread$SleepTask2.run(org.jruby.dist/RubyThread.java:1722)
        at org.jruby.RubyThread.executeTask(org.jruby.dist/RubyThread.java:1791)
        at org.jruby.RubyThread.executeTaskBlocking(org.jruby.dist/RubyThread.java:1765)
        at org.jruby.RubyThread.sleep(org.jruby.dist/RubyThread.java:1609)
        at org.jruby.RubyKernel.sleepCommon(org.jruby.dist/RubyKernel.java:899)
        at org.jruby.RubyKernel.sleep(org.jruby.dist/RubyKernel.java:884)
        at java.lang.invoke.DirectMethodHandle$Holder.invokeStatic(java.base@23/DirectMethodHandle$Holder)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0ac800.invoke(java.base@23/LambdaForm$MH)
        at java.lang.invoke.DelegatingMethodHandle$Holder.delegate(java.base@23/DelegatingMethodHandle$Holder)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0ad800.guard(java.base@23/LambdaForm$MH)
        at java.lang.invoke.DelegatingMethodHandle$Holder.delegate(java.base@23/DelegatingMethodHandle$Holder)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0ad800.guard(java.base@23/LambdaForm$MH)
        at java.lang.invoke.Invokers$Holder.linkToCallSite(java.base@23/Invokers$Holder)
        at home.kasuga.vcs.redis_minus_cluster_minus_client.lib.redis_client.cluster.pub_sub.️   {} spawn_worker #1(/home/kasuga/vcs/redis-cluster-client/lib/redis_client/cluster/pub_sub.rb:42)
        at java.lang.invoke.DirectMethodHandle$Holder.invokeStatic(java.base@23/DirectMethodHandle$Holder)
        at java.lang.invoke.LambdaForm$MH/0x000076068f2dd800.invoke(java.base@23/LambdaForm$MH)
        at java.lang.invoke.Invokers$Holder.invokeExact_MT(java.base@23/Invokers$Holder)
        at org.jruby.runtime.CompiledIRBlockBody.yieldDirect(org.jruby.dist/CompiledIRBlockBody.java:151)
        at org.jruby.runtime.IRBlockBody.yieldSpecific(org.jruby.dist/IRBlockBody.java:74)
        at org.jruby.runtime.Block.yieldSpecific(org.jruby.dist/Block.java:160)
        at org.jruby.RubyKernel.loop(org.jruby.dist/RubyKernel.java:1657)
        at java.lang.invoke.DirectMethodHandle$Holder.invokeStatic(java.base@23/DirectMethodHandle$Holder)
        at java.lang.invoke.DelegatingMethodHandle$Holder.reinvoke_L(java.base@23/DelegatingMethodHandle$Holder)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0d6c00.invoke(java.base@23/LambdaForm$MH)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0ad400.reinvoke(java.base@23/LambdaForm$MH)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0ad800.guard(java.base@23/LambdaForm$MH)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0ad400.reinvoke(java.base@23/LambdaForm$MH)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0ad800.guard(java.base@23/LambdaForm$MH)
        at java.lang.invoke.Invokers$Holder.linkToCallSite(java.base@23/Invokers$Holder)
        at home.kasuga.vcs.redis_minus_cluster_minus_client.lib.redis_client.cluster.pub_sub.️   {} spawn_worker #0(/home/kasuga/vcs/redis-cluster-client/lib/redis_client/cluster/pub_sub.rb:38)
        at java.lang.invoke.DirectMethodHandle$Holder.invokeStatic(java.base@23/DirectMethodHandle$Holder)
        at java.lang.invoke.LambdaForm$MH/0x000076068f0b0000.invoke(java.base@23/LambdaForm$MH)
        at java.lang.invoke.Invokers$Holder.invokeExact_MT(java.base@23/Invokers$Holder)
        at org.jruby.runtime.CompiledIRBlockBody.callDirect(org.jruby.dist/CompiledIRBlockBody.java:141)
        at org.jruby.runtime.MixedModeIRBlockBody.callDirect(org.jruby.dist/MixedModeIRBlockBody.java:105)
        at org.jruby.runtime.IRBlockBody.call(org.jruby.dist/IRBlockBody.java:66)
        at org.jruby.runtime.IRBlockBody.call(org.jruby.dist/IRBlockBody.java:60)
        at org.jruby.runtime.Block.call(org.jruby.dist/Block.java:146)
        at org.jruby.RubyProc.call(org.jruby.dist/RubyProc.java:359)
        at org.jruby.internal.runtime.RubyRunnable.run(org.jruby.dist/RubyRunnable.java:122)
        at java.lang.Thread.runWith(java.base@23/Thread.java:1588)
        at java.lang.Thread.run(java.base@23/Thread.java:1575)

[supercaracal]

No need to use Fiber in these test cases.