schedule: zephyr_ll_user: improve heap init and make it usable from user-space #23269

Job	Run time
manifest-check	2m 58s
LP64-WIP	3m 49s
build-windows (mnfst, tgl)	8m 57s
build-windows (mnfst, lnl)	9m 12s
build-linux (mnfst, lnl)	4m 6s
build-linux (mnfst, tgl)	4m 16s
build-linux (-d, mnfst, lnl)	4m 27s
build-linux (mnfst, imx8m imx8ulp)	4m 57s
build-linux (mnfst, imx8 imx8x)	5m 23s
build-windows (mnfst, ptl)	10m 4s
build-linux (mnfst, mtl)	4m 44s
build-windows (mnfst, imx8 imx8x)	9m 26s
build-windows (mnfst, tgl-h)	9m 26s
build-linux (mnfst, ptl)	6m 11s
build-windows (mnfst, mtl)	9m 17s
build-windows (mnfst, imx8m imx8ulp)	10m 42s
build-linux (mnfst, tgl-h)	4m 28s
build-windows (-d, mnfst, lnl)	8m 32s
build-linux (mnfst, wcl imx95)	6m 58s
compare-linux-win	30s
	2h 8m 23s

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