Tracking issue for StringIndexOutOfBoundsException in grok

**Logstash information**:

In some specific `grok` patterns, it is possible Logstash pipelines fail to start due to https://github.com/jruby/jruby/pull/8960.
The problem seems to be a concurrency issue with the multiline codec & grok-based plugin.
```
{:action=>LogStash::PipelineAction::Create/pipeline_id:pipeline2, :exception=>"Java::JavaLang::IllegalStateException", :message=>"Unable to configure plugins: (LoadError) load error: cabin/mixins/logger -- java.lang.StringIndexOutOfBoundsException: Index -1 out of bounds for length 16", :backtrace=>["org.logstash.config.ir.CompiledPipeline.(CompiledPipeline.java:137)", "org.logstash.execution.AbstractPipelineExt.initialize(AbstractPipelineExt.java:236)", "org.logstash.execution.AbstractPipelineExt$INVOKER$i$initialize.call(AbstractPipelineExt$INVOKER$i$initialize.gen)", "org.jruby.internal.runtime.methods.JavaMethod$JavaMethodN.call(JavaMethod.java:847)", "org.jruby.ir.runtime.IRRuntimeHelpers.instanceSuper(IRRuntimeHelpers.java:1379)", "org.jruby.ir.instructions.InstanceSuperInstr.interpret(InstanceSuperInstr.java:139)", "org.jruby.ir.interpreter.InterpreterEngine.processCall(InterpreterEngine.java:363)", "org.jruby.ir.interpreter.StartupInterpreterEngine.interpret(StartupInterpreterEngine.java:66)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.INTERPRET_METHOD(MixedModeIRMethod.java:128)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.call(MixedModeIRMethod.java:115)", "org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:446)", "org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:92)", "org.jruby.RubyClass.newInstance(RubyClass.java:950)", "org.jruby.RubyClass$INVOKER$i$newInstance.call(RubyClass$INVOKER$i$newInstance.gen)", "org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:446)", "org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:92)", "org.jruby.ir.instructions.CallBase.interpret(CallBase.java:548)", "org.jruby.ir.interpreter.InterpreterEngine.processCall(InterpreterEngine.java:363)", "org.jruby.ir.interpreter.StartupInterpreterEngine.interpret(StartupInterpreterEngine.java:66)", "org.jruby.ir.interpreter.InterpreterEngine.interpret(InterpreterEngine.java:88)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.INTERPRET_METHOD(MixedModeIRMethod.java:238)", "org.jruby.interna...
```

Workaround is to temporarily enable configuration reload so that it auto-retries to restart and might not get the concurrency issue.

---

This tracking issue is to remember to upgrade Logstash JRuby to 9.4.14.0 or 10.0.3.0, which seem to include the fix.

We temporarily upgraded to [9.4.14.0](https://github.com/elastic/logstash/commit/fe4a735c64b710796fd21144166ed9b9b8832e85), but it got [reverted](https://github.com/elastic/logstash/commit/096f1a3818ba43b3ed3258c10f1fceb81ad8839f) due to side effect we've discovered.