fix: Add default values to DaprClientProperties for Spring Boot apps

[siri-varma]

When starting a Spring Boot application without explicitly setting DaprClientProperties, fields are now initialized with Dapr's standard defaults instead of null: httpEndpoint=http://localhost, grpcEndpoint=localhost, httpPort=3500, grpcPort=50001, apiToken=null.

Fixes #1566

Description

Please explain the changes you've made

Issue reference

We strive to have all PR being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: #1566

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation

[Copilot]

Pull request overview

This PR aims to ensure DaprClientProperties in the Spring Boot integration are initialized with Dapr-standard defaults when users don’t explicitly configure dapr.client.*, addressing #1566.

Changes:

• Add default endpoint/port constants and initialize DaprClientProperties fields with those defaults.
• Extend DaprClientPropertiesTest with new assertions for defaults (no-arg constructor and Spring context binding).
• Update the setter-based test to validate non-default/custom values.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
dapr-spring/dapr-spring-boot-properties/src/main/java/io/dapr/spring/boot/properties/client/DaprClientProperties.java	Introduces default constants and non-null default field initialization for client endpoints/ports.
dapr-spring/dapr-spring-boot-properties/src/test/java/io/dapr/spring/boot/properties/client/DaprClientPropertiesTest.java	Adds/updates tests validating default values and property mapping behavior.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.41%. Comparing base (f63a4a4) to head (f83cd72).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1697      +/-   ##
============================================
- Coverage     79.53%   79.41%   -0.13%     
+ Complexity     2193     2189       -4     
============================================
  Files           237      237              
  Lines          6577     6577              
  Branches        730      730              
============================================
- Hits           5231     5223       -8     
  Misses          990      990              
- Partials        356      364       +8     

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