Replace mvnw with mvn in README.md because mvnw doesn't work with run-in-docker.sh

[sekikn]

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  Not required since it's just a minor documentation fix

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  fixes [BUG] The section about development in docker in README.md has incorrect commands #22974

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Summary by cubic

Update README to replace mvnw with mvn in run-in-docker.sh examples and troubleshooting, since mvnw doesn’t work inside the Docker container. Fixes #22974 and prevents build failures when following the docs.

^{Written for commit 262ebcd. Summary will update on new commits.}

[cubic-dev-ai]

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