Remove always-on language feature flag: DotlessFloat32Literal

[T-Gro]

LanguageFeature.DotlessFloat32Literal has shipped since F# 5.0 and is enabled for every selectable language version (the minimum accepted --langversion is 8.0). Its feature flag can therefore never be turned off, so it is dead configuration. This issue removes the flag and collapses the guarded code to its enabled behaviour.

What to remove

• The DotlessFloat32Literal case in LanguageFeatures.fs and LanguageFeatures.fsi
• Its entry in the features map and its GetFeatureString arm
• The featureDotlessFloat32Literal string in FSComp.txt
• Every SupportsFeature LanguageFeature.DotlessFloat32Literal / checkLanguageFeatureAndRecover … DotlessFloat32Literal guard — keep only the enabled path and delete the legacy branch
• Adjust affected tests and baselines accordingly

Consequence: --disableLanguageFeature:DotlessFloat32Literal is no longer a recognised feature name.

Version mapping

fsharp/src/Compiler/Facilities/LanguageFeatures.fs

Line 162 in ea778bb

LanguageFeature.DotlessFloat32Literal, languageVersion50

Feature string

fsharp/src/Compiler/FSComp.txt

Line 1573 in ea778bb

featureDotlessFloat32Literal,"dotless float32 literal"

Part of #20139