Remove always-on language feature flag: ErrorReportingOnStaticClasses

[T-Gro]

LanguageFeature.ErrorReportingOnStaticClasses has shipped since F# 8.0 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 ErrorReportingOnStaticClasses case in LanguageFeatures.fs and LanguageFeatures.fsi
• Its entry in the features map and its GetFeatureString arm
• The featureErrorReportingOnStaticClasses string in FSComp.txt
• Every SupportsFeature LanguageFeature.ErrorReportingOnStaticClasses / checkLanguageFeatureAndRecover … ErrorReportingOnStaticClasses guard — keep only the enabled path and delete the legacy branch
• Adjust affected tests and baselines accordingly

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

Version mapping

fsharp/src/Compiler/Facilities/LanguageFeatures.fs

Line 206 in ea778bb

LanguageFeature.ErrorReportingOnStaticClasses, languageVersion80

Feature string

fsharp/src/Compiler/FSComp.txt

Line 1599 in ea778bb

featureErrorReportingOnStaticClasses,"Error reporting on static classes"

Part of #20139