Tweak Camera3D `size` property hint to make dragging more useful #12404

Job	Run time
📊 Static checks / Code style, file formatting, and docs	48s
🐧 Linux / Editor w/ Mono (target=editor)	5m 0s
🍎 macOS / Editor (target=editor, tests=yes)	4m 30s
🐧 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)	18m 22s
🍏 iOS / Template (target=template_release)	3m 6s
🤖 Android / Template (target=template_release)	4m 28s
🍎 macOS / Template (target=template_release)	3m 59s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	9m 45s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	9m 39s
🌐 Web / Template (target=template_release)	1m 19s
🐧 Linux / Template w/ Mono (target=template_release)	2m 3s
🏁 Windows / Editor (target=editor, tests=yes)	9m 33s
🐧 Linux / Minimal template (target=template_release, everything disabled)	1m 57s
🏁 Windows / Template (target=template_release)	8m 17s
🪲 Godot CPP / Build and test Godot CPP	9m 47s
	1h 32m 33s

Provide feedback