fix(spring): switch camelcase conversion logic to use JavaStyle

[emmileaf]

This PR switches camelcase handling to use align with logic used in generating client libraries, e.g. here. However, it introduces no updates to golden tests for the spring composers, and my local test to regenerate GoogleCloudPlatform/spring-cloud-gcp#1449 using this branch also showed no diff.

I think spring-cloud-gcp enforces stricter checkstyle rules (fail on warning) than what is used for the client libraries, so a corresponding change has been made on that side to suppress this for a number of files with abbreviation handling edge cases: GoogleCloudPlatform/spring-cloud-gcp#1455

• Some examples of edge cases observed: getOSPolicyAssignmentSettings, IDSSettings

[conventional-commit-lint-gcf]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot
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[sonarqubecloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

100.0% Coverage
0.0% Duplication

[zhumin8]

Thanks for making these changes. Although no difference in generated code is made, it's good to be in sync with client library for maintenance.