Removes explicit dapr stop from examples for short-running apps

[elena-kolevska]

Description

While validating the 1.13 rc1 I ran into the following 3 issues:

• ./validate.sh invoke-custom-data (❌ failed to stop app id invoke-caller: couldn't find app id invoke-caller)

• ./validate.sh w3c-tracing (❌ failed to stop app id invoke-caller: couldn't find app id invoke-caller)

• ./validate.sh demo_workflow (❌ details = "error starting workflow 'hello_world_wf': unable to start workflow: failed to start orchestration: error from internal actor: an active workflow with ID 'exampleInstanceID' already exists"
  == APP == debug_error_string = "UNKNOWN:Error received from peer ipv4:127.0.0.1:50001 {created_time:"2024-02-14T14:14:09.774273+00:00", grpc_status:13, grpc_message:"error starting workflow 'hello_world_wf': unable to start workflow: failed to start orchestration: error from internal actor: an active workflow with ID 'exampleInstanceID' already exists"}")

This PR addresses the first two issues. The reason for this is a change of behaviour in Dapr, which now properly catches SIGTERM signals. The examples use dapr run to run the apps and the dapr cli sends a SIGTERM when an application finishes execution. That's why the tests broke now.
This behaviour is only evident for short-running scripts.

I updated the examples to not try to stop the dapr instance explicitly.

Checklist

• Code compiles correctly
• Created/updated tests

[codecov]

Codecov Report

Attention: 16 lines in your changes are missing coverage. Please review.

Comparison is base (fc0e9d1) 86.37% compared to head (e656227) 86.18%.
Report is 7 commits behind head on main.

Files	Patch %	Lines
dapr/clients/health.py	72.72%	9 Missing ⚠️
dapr/aio/clients/grpc/client.py	92.15%	4 Missing ⚠️
dapr/actor/client/proxy.py	57.14%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #674      +/-   ##
==========================================
- Coverage   86.37%   86.18%   -0.19%     
==========================================
  Files          79       82       +3     
  Lines        4094     4170      +76     
==========================================
+ Hits         3536     3594      +58     
- Misses        558      576      +18     

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