llext: remove unneeded data and functions #20262

Job	Run time
LP64-WIP	3m 58s
manifest-check	54s
build-windows (ptl)	6m 36s
build-windows (imx8 imx8x imx8m imx8ulp)	9m 18s
build-windows (mtl lnl)	7m 27s
build-linux (zmain, mtl lnl)	5m 53s
build-linux (mnfst, imx8 imx8x imx8m imx8ulp)	6m 37s
build-linux (zmain, tgl tgl-h)	5m 32s
build-linux (mnfst, --all)	14m 40s
build-windows (-d, lnl)	6m 27s
build-linux (mnfst, ptl)	5m 1s
build-linux (zmain, imx8 imx8x imx8m imx8ulp)	7m 4s
build-linux (mnfst, mtl lnl)	5m 58s
build-linux (mnfst, tgl tgl-h)	5m 33s
build-linux (zmain, ptl)	4m 43s
build-linux (-d, mnfst, lnl)	5m 14s
build-windows (tgl tgl-h)	7m 12s
compare-linux-win	36s
	1h 48m 43s

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