build: xtensa-build-zephyr.py: remove Intel ehl target #20429

Job	Run time
LP64-WIP	4m 6s
manifest-check	46s
build-windows (imx8 imx8x imx8m imx8ulp)	8m 15s
build-windows (ptl)	6m 7s
build-windows (-d, lnl)	6m 36s
build-windows (tgl tgl-h)	7m 32s
build-windows (mtl lnl)	7m 12s
build-linux (mnfst, mtl lnl)	5m 51s
build-linux (mnfst, imx8 imx8x imx8m imx8ulp)	6m 35s
build-linux (mnfst, tgl tgl-h)	5m 33s
build-linux (mnfst, ptl)	4m 41s
build-linux (mnfst, --all)	14m 27s
build-linux (zmain, mtl lnl)	5m 42s
build-linux (zmain, ptl)	5m 17s
build-linux (zmain, imx8 imx8x imx8m imx8ulp)	6m 27s
build-linux (-d, mnfst, lnl)	4m 38s
build-linux (zmain, tgl tgl-h)	5m 22s
compare-linux-win	32s
	1h 45m 39s

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