fix: remove CSS `@layer` rule from static CSS bundle #18008

Job	Run time
check-bundle-size	3m 59s
Install Dependencies	1m 11s
reuse-compliance	11s
Build (18)	1m 38s
lint	1m 40s
Build (19)	2m 12s
test / Cypress (base, 18)	2m 10s
test / Cypress (base, 19)	2m 47s
test / Cypress (charts, 18)	3m 19s
test / Cypress (charts, 19)	1m 41s
test / Cypress (cypress-commands, 18)	1m 37s
test / Cypress (cypress-commands, 19)	2m 42s
test / Cypress (main/src/components, 18)	5m 49s
test / Cypress (main/src/components, 19)	6m 5s
test / Cypress (main/src/internal, 18)	1m 40s
test / Cypress (main/src/internal, 19)	2m 25s
test / Cypress (compat, 18)	1m 57s
test / Cypress (compat, 19)	2m 27s
deploy-next-docs	0s
test / Combine Coverage	6s
	45m 36s

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