investigate fmt-maven-plugin upgrade error

[zhumin8]

fmt-maven-plugin upgrade to 2.13 is failing on error for ci/lint and ci/showcase, but pass for other ci checks. see https://github.com/googleapis/sdk-platform-java/pull/3544#issuecomment-2576147488

Found this old attempt to upgrade failing with Java incompatible: https://github.com/googleapis/sdk-platform-java/pull/941 unsure if related. One other clue is https://github.com/googleapis/sdk-platform-java/pull/2533, shows com.google.googlejavaformat:google-java-format version in project is not uniformed. and google-java-format 1.14 requires java 11 (ref: https://github.com/googleapis/sdk-platform-java/issues/952)