Fix kafka permission in dockerfile

[zzh8829]

Changes

Before the fix, kafka will crash immediate when running in docker compose on m1 mac, unsure if this also happens in other environments or platform.

How to reproduce the issue

docker compose up --no-deps --build kafka

logs

kafka  | Error opening zip file or JAR manifest missing : /tmp/opentelemetry-javaagent.jar Error occurred during initialization of VM agent library failed Agent_OnLoad: instrument
kafka exited with code 1

inspecting the jar showing incorrect permission

/ $ ls -al /tmp/opentelemetry-javaagent.jar 
-rw-------    1 root     root      21007939 Apr 12 00:45 /tmp/opentelemetry-javaagent.jar

after the fix

/ $ ls -al /tmp/opentelemetry-javaagent.jar 
-rw-------    1 appuser  appuser   21007939 Apr 12 00:45 /tmp/opentelemetry-javaagent.jar

Merge Requirements

For new features contributions please make sure you have completed the following essential items:

• [x] CHANGELOG.md updated to document new feature additions
• [x] Appropriate documentation updates in the docs
• [x] Appropriate Helm chart updates in the helm-charts

Maintainers will not merge until the above have been completed. If you're unsure which docs need to be changed ping the @open-telemetry/demo-approvers.