Clean up SerilaiInputHandler #1219

Job	Run time
build-frontend	25s
getvars / get-vars	8s
build-firmware (Wemos-D1-Mini-ESP32)	1m 12s
build-firmware (Wemos-Lolin-S2-Mini)	1m 41s
build-firmware (Wemos-Lolin-S3)	1m 28s
build-firmware (Wemos-Lolin-S3-Mini)	1m 30s
build-firmware (Waveshare_esp32_s3_zero)	1m 41s
build-firmware (Pishock-2023)	1m 12s
build-firmware (Pishock-Lite-2021)	1m 17s
build-firmware (Seeed-Xiao-ESP32C3)	1m 22s
build-firmware (Seeed-Xiao-ESP32S3)	1m 32s
build-firmware (DFRobot-Firebeetle2-ESP32E)	1m 24s
build-firmware (OpenShock-Core-V1)	1m 32s
build-firmware (OpenShock-Core-V2)	1m 42s
build-staticfs	31s
merge-partitions (Wemos-D1-Mini-ESP32)	17s
merge-partitions (Wemos-Lolin-S2-Mini)	10s
merge-partitions (Wemos-Lolin-S3)	16s
merge-partitions (Wemos-Lolin-S3-Mini)	9s
merge-partitions (Waveshare_esp32_s3_zero)	18s
merge-partitions (Pishock-2023)	9s
merge-partitions (Pishock-Lite-2021)	9s
merge-partitions (Seeed-Xiao-ESP32C3)	10s
merge-partitions (Seeed-Xiao-ESP32S3)	18s
merge-partitions (DFRobot-Firebeetle2-ESP32E)	10s
merge-partitions (OpenShock-Core-V1)	11s
merge-partitions (OpenShock-Core-V2)	16s
checkpoint-build	1s
cdn-upload-version-info	0s
cdn-upload-firmware	0s
cdn-bump-version	0s
checkpoint-cdn	0s
release	0s
	21m 11s

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