chore(sdk-platform-java): restore GEMINI.md and DEVELOPMENT.md #17254

Job	Run time
group_id_check_for_maps_libraries	8m 17s
owlbot-py	1m 20s
gapic-bom	1m 41s
owlbot-yaml	1m 1s
generate-readme	1m 5s
root-pom	1m 43s
gitignore_correctness	1m 3s
package_name_check	1m 2s
	17m 12s

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