Remove Feature.globalOnlyImports (#19881)

This is dead code. This logic is now handled by
`Features.handleGlobalLanguageImport`.

Author: odersky

compiler/src/dotty/tools/dotc/config/Feature.scala

@@ -33,8 +33,6 @@ object Feature:
   val captureChecking = experimental("captureChecking")
   val into = experimental("into")
 
-  val globalOnlyImports: Set[TermName] = Set(pureFunctions, captureChecking)
-
   /** Is `feature` enabled by by a command-line setting? The enabling setting is
    *
    *       -language:<prefix>feature

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -30,7 +30,7 @@ import scala.annotation.tailrec
 import rewrites.Rewrites.{patch, overlapsPatch}
 import reporting.*
 import config.Feature
-import config.Feature.{sourceVersion, migrateTo3, globalOnlyImports}
+import config.Feature.{sourceVersion, migrateTo3}
 import config.SourceVersion.*
 import config.SourceVersion
 import dotty.tools.dotc.config.MigrationVersion