Fix C# epsilon compiler error on double precision build #24340

Job	Run time
📊 Static checks / Code style, file formatting, and docs	2m 51s
🍏 iOS / Template (target=template_release)	2m 32s
🐧 Linux / Editor w/ Mono (target=editor)	38m 26s
🐧 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)	39m 16s
🍎 macOS / Editor (target=editor, tests=yes)	4m 37s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	4m 33s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	34m 1s
🏁 Windows / Editor (target=editor, tests=yes)	48m 30s
🍎 macOS / Template (target=template_release)	4m 40s
🌐 Web / Template w/o threads (target=template_release, threads=no)	4m 32s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	29m 0s
🏁 Windows / Template (target=template_release)	32m 46s
🐧 Linux / Template w/ Mono (target=template_release)	2m 22s
🐧 Linux / Minimal template (target=template_release, everything disabled)	1m 48s
🤖 Android / Template (target=template_release)	30m 36s
🪲 Godot CPP / Build and test Godot CPP	6m 51s
	4h 47m 21s

Provide feedback