fix(o11y): remove `gpc.client.language` attribute #17236

Job	Run time
owlbot-yaml	1m 18s
gitignore_correctness	1m 1s
gapic-bom	1m 57s
root-pom	1m 35s
package_name_check	1m 19s
generate-readme	1m 27s
group_id_check_for_maps_libraries	8m 15s
owlbot-py	1m 23s
	18m 15s

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