Deprecate `setExtra` #6760

Job	Run time
cancel-previous-workflow	2s
Dart 2.18 on ubuntu	7m 55s
Dart 2.19 on ubuntu	8m 17s
Dart 3.0 on ubuntu	7m 47s
Dart 3.1 on ubuntu	7m 19s
Dart 3.2 on ubuntu	9m 2s
Dart 3.3 on ubuntu	8m 28s
Dart 3.4 on ubuntu	9m 0s
Dart stable on ubuntu	12m 52s
Dart beta on ubuntu	10m 36s
Dart stable on windows	10m 43s
Dart stable on macos	10m 40s
analyze / cancel-previous-workflow	4s
analyze / analyze	46s
analyze / package-analysis	1m 43s
	1h 45m 14s

Provide feedback