fix: `ImageBuildSpec` `build_file` feature #8268

Job	Run time
check-if-code-change	18s
golang-lint (container-engine-lib)	26s
golang-lint (contexts-config-store)	16s
golang-lint (grpc-file-transfer/golang)	17s
golang-lint (metrics-library/golang)	12s
golang-lint (name_generator)	16s
golang-lint (api/golang)	13s
golang-lint (core/server)	33s
golang-lint (core/launcher)	19s
golang-lint (engine/server)	22s
golang-lint (engine/launcher)	18s
golang-lint (internal_testsuites/golang)	14s
golang-lint (cli/cli)	34s
	4m 18s

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