[BUG] Debian and rpm Upgrade functionality is broken

What is the bug?
Upgrading performance analyzer to a higher version is broken from opendistro 1.10.1.

1. Fix the incorrect binary path in the systemd service.
2. After manually changing the binary path, it throws error

performance-analyzer-agent-cli[2042984]: Caused by: java.lang.ClassNotFoundException: com.amazon.opendistro.elasticsearch.performanceanalyzer.PerformanceAnalyzerApp

3. Need to revisit the postrm as it basically removes everything.
   Related issue: https://github.com/opendistro-for-elasticsearch/performance-analyzer/issues/235

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

What is the expected behavior?
A clear and concise description of what you expected to happen.

What is your host/environment?

• OS: [e.g. iOS]
• Version [e.g. 22]
• Plugins

Do you have any screenshots?
If applicable, add screenshots to help explain your problem.

Do you have any additional context?
Add any other context about the problem.

Start by inspecting the Debian and rpm upgrade packaging, especially the systemd service binary path and the postrm script. Reproduce an upgrade from opendistro 1.10.1, then verify that the service starts without the reported ClassNotFoundException and that postrm removes only intended files.