fix: [JAVA][resttemplate] avoid unused Spring imports when generateClientAsBean is false

[Natarajan717]

Fixes #20657

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Description of the PR

Fixes #20657

When generating a Java client with --library resttemplate and default settings (generateClientAsBean=false), ApiClient.java and API classes still unconditionally imported org.springframework.beans.factory.annotation.Autowired and org.springframework.stereotype.Component, leading to unused import warnings.

This PR wraps these imports in {{#generateClientAsBean}}...{{/generateClientAsBean}} in both:

• modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache
• modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/api.mustache

(matching the behavior already implemented in webclient and restclient).

Related Issue

Fixes #20657
cc: @wing328

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Summary by cubic

Fixes #20657: the Java resttemplate templates for ApiClient and API classes now only emit Spring @Autowired and @Component imports when generateClientAsBean is true. Generated clients no longer contain unused Spring imports with the default generateClientAsBean=false configuration, matching the behavior already present in webclient and restclient. Regression tests cover both flag values.

^{Written for commit f9c406f. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 51 files

_{Re-trigger cubic}