Change how ImageTexture's image is defined #26243

Job	Run time
📊 Static checks / Code style, file formatting, and docs	5m 23s
🍏 iOS / Template (target=template_release)	2m 46s
🍎 macOS / Editor (target=editor, tests=yes)	6m 48s
🐧 Linux / Editor w/ Mono (target=editor)	8m 35s
🍎 macOS / Template (target=template_release)	3m 7s
🤖 Android / Template (target=template_release)	5m 18s
🐧 Linux / Editor with doubles and GCC sanitizers (target=editor, tests=yes, dev_build=yes, scu_build=yes, precision=double, use_asan=yes, use_ubsan=yes, linker=gold)	19m 54s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	5m 3s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	8m 50s
🏁 Windows / Editor (target=editor, tests=yes)	12m 47s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	9m 3s
🌐 Web / Template w/o threads (target=template_release, threads=no)	5m 8s
🏁 Windows / Template (target=template_release)	9m 3s
🐧 Linux / Template w/ Mono (target=template_release)	3m 42s
🐧 Linux / Minimal template (target=template_release, everything disabled)	2m 24s
🪲 Godot CPP / Build and test Godot CPP	8m 3s
	1h 55m 54s

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