Use SEC1 point encoding instead of integer X/Y for variable point ECC mul test #6272

Job	Run time
Clang Tidy	1m 48s
Linux (gcc, shared)	1m 57s
Analysis (coverage, gcc, ubuntu-24.04)	25m 21s
Linux (gcc, amalgamation)	1m 17s
Analysis (sanitizer, clang, ubuntu-24.04)	19m 48s
Linux (gcc, static)	1m 34s
Analysis (valgrind, clang, ubuntu-24.04)	32m 16s
macOS (shared, xcode, macos-13)	22m 20s
Linux (clang, shared)	2m 2s
macOS (amalgamation, xcode, macos-13)	10m 41s
Analysis (fuzzers, gcc, ubuntu-24.04)	11m 21s
macOS (shared, xcode, macos-14)	6m 13s
Analysis (lint, gcc, ubuntu-24.04)	54s
macOS (amalgamation, xcode, macos-14)	1m 14s
Analysis (format, gcc, ubuntu-24.04)	33s
Analysis (limbo, gcc, ubuntu-24.04)	48s
Special (examples, gcc, ubuntu-24.04)	49s
Special (minimized, gcc, ubuntu-24.04)	25s
Windows (shared, x86_64, windows-2022)	6m 35s
Special (bsi, gcc, ubuntu-24.04)	1m 11s
Windows (static, x86_64, windows-2022)	4m 9s
Cross (cross-i386, gcc, ubuntu-22.04)	2m 41s
Special (docs, gcc, ubuntu-24.04)	1m 2s
Cross (cross-arm32, gcc, ubuntu-24.04)	16m 24s
Windows (amalgamation, x86_64, windows-2022)	5m 4s
Special (no_pcurves, gcc, ubuntu-24.04)	1m 15s
Cross (cross-arm64, gcc, ubuntu-24.04)	17m 0s
Windows (shared, x86, windows-2022)	6m 47s
Cross (cross-ppc64, gcc, ubuntu-24.04)	6m 30s
Cross (cross-mips64, gcc, ubuntu-24.04)	7m 1s
Cross (cross-android-arm64, clang, ubuntu-24.04)	5m 30s
Cross (static, gcc, windows-2022, make)	4m 14s
Cross (cross-ios-arm64, xcode, macos-13)	16m 13s
	4h 2m 57s

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